Updated on 2024/04/08

写真a

 
KIM DaeGwi
 
Organization
Graduate School of Engineering Division of Physics and Electronics Professor
School of Engineering Department of Physics and Electronics
Title
Professor
Affiliation
Institute of Engineering
Affiliation campus
Nakamozu Campus

Position

  • Graduate School of Engineering Division of Physics and Electronics 

    Professor  2022.04 - Now

  • School of Engineering Department of Physics and Electronics 

    Professor  2022.04 - Now

Degree

  • Doctor of Science ( Osaka City University )

Research Areas

  • Nanotechnology/Materials / Nanomaterials  / ナノマテリアル科学・工学

  • Natural Science / Semiconductors, optical properties of condensed matter and atomic physics  / Optical properties of material

  • Nanotechnology/Materials / Nanomaterials  / ナノマテリアル科学・工学

  • Natural Science / Semiconductors, optical properties of condensed matter and atomic physics  / Optical properties of material

Research Interests

  • 半導体ナノ粒子

  • 水熱合成法

  • Layer-by-layer法

  • 半導体ナノ粒子超格子

  • 半導体ナノ粒子間のエネルギー共鳴

  • 半導体ナノ粒子間のエネルギー移動

  • 水熱合成法

  • 半導体ナノ粒子

  • 半導体ナノ粒子超格子

  • 半導体ナノ粒子間のエネルギー共鳴

  • 半導体ナノ粒子間のエネルギー移動

  • Layer-by-layer法

Research subject summary

  • (1)水熱合成法による種々の半導体ナノ粒子の作製
    (2)半導体ナノ粒子の光学特性の温度依存性
    (3)ナノ粒子積層構造の作製と光学特性
    (4)半導体ナノ粒子間のエネルギー移動メカニズムの解明
    (5)局在表面プラズモンを利用した発光増強・消光の制御
    (6)ナノ粒子規則配列構造の作製とナノ粒子間共鳴相互作用

Research Career

  • Optical properties of semiconductor nanoparticles

    Semiconductor, nanoparticles, exciton 

    2000.04 - Now 

  • Optical properties of oxide-semiconductor thin films

    oxide semiconductor, thin film, exciton 

    1997.04 - 2013.03 

Professional Memberships

  • THE PHYSICAL SOCIETY OF JAPAN

      Domestic

  • Materials research society of Japan

      Domestic

  • Society of nano science and technology

      Domestic

  • Chemical Society of Japan

      Domestic

  • Japan society of applied physics

      Domestic

  • Japan society of applied physics

  • THE PHYSICAL SOCIETY OF JAPAN

  • Society of nano science and technology

  • Materials research society of Japan

  • Chemical Society of Japan

▼display all

Awards

  • 第13回日本MRS学術シンポジウム奨励賞

    2001  

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    Country:Japan

Job Career (off-campus)

  • Osaka Metropolitan University School of Engineering Department of Physics and Electronics

    2022.04 - Now

  • Osaka City University   Graduate School of Engineering

    2012.10 - Now

  • Osaka City University   Graduate School of Engineering

    2007.04 - 2012.09

  • Osaka City University   Graduate School of Engineering

    2002.10 - 2007.03

Education

  • Osaka City University   The second semester of doctoral program   Accomplished credits for doctoral program

    1994.04 - 1997.03

  • Osaka City University   The first semester of doctoral program   Graduated/Completed

    - 1994.03

Papers

  • Controlling the dimension of the quantum resonance in CdTe quantum dot superlattices fabricated via layer-by-layer assembly Reviewed

    T. G. Lee, K. Enomoto, K. Ohshiro, D. Inoue, T. Kikitsu, H.-D. Kim, Y.-J. Pu, and D. Kim

    Nature Commun.   11   5471   2020

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    Authorship:Last author, Corresponding author   Publishing type:Research paper (scientific journal)   International / domestic magazine:International journal  

    Repository URL: http://hdl.handle.net/10466/0002000068

  • Probing of Photocarrier Electrons and Excitons at an Organic Monolayer Film Studied by Two-Photon Photoemission Spectroscopy

    Nojima S.

    Journal of Physical Chemistry C   128 ( 5 )   2043 - 2051   2024.02( ISSN:19327447

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  • Deposition and optical constants evaluation of multilayered zinc-based semiconductor nanoparticle films assembled by spray-assisted Layer-by-Layer method

    Nakatani Kaichi, Kim DaeGwi, Shim YongGu

    Journal of Ternary and Multinary Compounds   2023 ( 0 )   38 - 42   2024

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    Multilayered films of ZnS and ZnSe were prepared by spray-assisted layer-by-layer assembly. The thickness and optical constants of the fabricated thin films were analyzed by spectroscopic ellipsometry. The results showed that homogeneous nanoparticle multilayer films can be formed using the spray assisted method as well as the dipping method.

    DOI: 10.57386/tmc.2023.0_38

  • Intrinsic characteristics of Si solar cells coated with thick luminescence down-shifting sol-gel glass films

    Idutsu Y.

    Japanese Journal of Applied Physics   62 ( SK )   2023.08( ISSN:00214922

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  • Optical constants of multilayered colloidal ZnSe nanoparticles

    Shim Y.G.

    Thin Solid Films   768   2023.03( ISSN:00406090

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  • Temperature-dependent photoluminescence properties of water-soluble CuInS<inf>2</inf>and CuInS<inf>2</inf>/ZnS quantum dots

    Iida K.

    Journal of Applied Physics   132 ( 19 )   2022.11( ISSN:00218979

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  • Temperature‐Dependent Exciton Dynamics in CdTe Quantum Dot Superlattices Fabricated via Layer‐by‐Layer Assembly

    TaeGi Lee, Kazuma Ohshiro, Taichi Watanabe, Kim Hyeon‐Deuk, DaeGwi Kim

    Advanced Optical Materials   10 ( 11 )   2022.06

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/adom.202102781

  • Intrinsic luminescence-downshifting effects of Zn-based Mn-doped nanoparticle layers on Si solar cells

    Idutsu Y.

    Japanese Journal of Applied Physics   61 ( 6 )   2022.06( ISSN:00214922

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  • Hydrothermal synthesis of water-soluble Mn- and Cu-doped CdSe quantum dots with multi-shell structures and their photoluminescence properties

    Nishimura H.

    RSC Advances   12 ( 10 )   6255 - 6264   2022

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  • Origin of photoluminescence of water-soluble CuInS<inf>2</inf>quantum dots prepared: Via a hydrothermal method

    Iida K.

    RSC Advances   11 ( 53 )   33186 - 33191   2021.10

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  • Water-soluble ZnSe/ZnS:Mn/ZnS quantum dots convert UV to visible light for improved Si solar cell efficiency

    Nishimura H.

    Journal of Materials Chemistry C   9 ( 2 )   693 - 701   2021.01( ISSN:20507534

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  • Selective Hydrothermal Synthesis of Water-Soluble CdTe and CdTe/CdS Colloidal Quantum Dots by Controlling the Te/Cd Molar Ratio of the Precursor Solution

    Shimura K.

    Bulletin of the Chemical Society of Japan   94 ( 12 )   2880 - 2885   2021( ISSN:00092673

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  • Controlling the dimension of the quantum resonance in CdTe quantum dot superlattices fabricated via layer-by-layer assembly

    TaeGi Lee, Kazushi Enomoto, Kazuma Ohshiro, Daishi Inoue, Tomoka Kikitsu, Kim Hyeon-Deuk, Yong-Jin Pu, DaeGwi Kim

    Nature Communications   11 ( 1 )   2020.12

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    Publishing type:Research paper (scientific journal)  

    <title>Abstract</title>
    In quantum dot superlattices, wherein quantum dots are periodically arranged, electronic states between adjacent quantum dots are coupled by quantum resonance, which arises from the short-range electronic coupling of wave functions, and thus the formation of minibands is expected. Quantum dot superlattices have the potential to be key materials for new optoelectronic devices, such as highly efficient solar cells and photodetectors. Herein, we report the fabrication of CdTe quantum dot superlattices via the layer-by-layer assembly of positively charged polyelectrolytes and negatively charged CdTe quantum dots. We can thus control the dimension of the quantum resonance by independently changing the distances between quantum dots in the stacking (out-of-plane) and in-plane directions. Furthermore, we experimentally verify the miniband formation by measuring the excitation energy dependence of the photoluminescence spectra and detection energy dependence of the photoluminescence excitation spectra.

    DOI: 10.1038/s41467-020-19337-0

    Other URL: http://www.nature.com/articles/s41467-020-19337-0

  • Spectroscopic ellipsometry of monolayered CdS nanoparticles assembled by layer-by-layer method

    Shim Y.G.

    Journal of Applied Physics   128 ( 7 )   2020.08( ISSN:00218979

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  • Modulation of Characteristics of Si Solar Cells by Luminescence-Downshifting Zn-Based Nanoparticles with Mn doped

    Idutsu Y.

    Conference Record of the IEEE Photovoltaic Specialists Conference   2020-June   0234 - 0237   2020.06( ISSN:01608371 ( ISBN:9781728161150

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  • Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands

    Lee Y.S.

    Nanoscale   12 ( 13 )   7124 - 7133   2020.04( ISSN:20403364

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  • Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands Reviewed

    Y.-S. Lee, T. Ito, K. Shimura, T. Watanabe, H.-B. Bu, H.-D. Kim, and D. Kim

    Nanoscale   2020

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    Publishing type:Research paper (scientific journal)   Kind of work:Joint Work  

  • Spectroscopic ellipsometry of monolayered CdS nanoparticles assembled by layer-by-layer method Reviewed

    Y. G. Shim, A. Kitano, K. Wakita, and D. Kim

    J. Appl. Phys.   128   075303   2020

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    Authorship:Last author   Publishing type:Research paper (scientific journal)   International / domestic magazine:International journal  

  • Spectroscopic ellipsometry of monolayered CdS nanoparticles assembled by layer-by-layer method Reviewed

    Y. G. Shim, A. Kitano, K. Wakita, D. Kim

    J. Appl. Phys.   128   075303   2020

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    Authorship:Last author   Publishing type:Research paper (scientific journal)   International / domestic magazine:International journal  

  • Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands Reviewed

    Y.-S. Lee, T. Ito, K. Shimura, T. Watanabe, H.-B. Bu, H.-D. Kim, D. Kim

    Nanoscale   2020

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    Publishing type:Research paper (scientific journal)  

  • Photoluminescence ON/OFF switching of CdSe/ZnS core/shell quantum dots coated with diarylethene ligands Reviewed

    Y. Seto, R. Yamada, D. Kitagawa, D. Kim, and S. Kobatake

    Chemistry Letters   48   1394 - 1397   2019.11

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    Publishing type:Research paper (scientific journal)   Kind of work:Joint Work  

  • Photoluminescence ON/OFF switching of CdSe/ZnS core/shell quantum dots coated with diarylethene ligands Reviewed

    Y. Seto, R. Yamada, D. Kitagawa, D. Kim, S. Kobatake

    Chemistry Letters   48   1394 - 1397   2019.11

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  • Synthesis of Mn-doped ZnSe-ZnS alloy quantum dots by a hydrothermal method Reviewed

    H. Nishimura, Y. Lin, M. Hizume, T. Taniguchi, N. Shigekawa, T. Takagi, S. Sobue, S. Kawai, E. Okuno, and D. Kim

    Chemistry Letters   48   1081 - 1083   2019.09

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    Publishing type:Research paper (scientific journal)   Kind of work:Joint Work  

  • Synthesis of Mn-doped ZnSe-ZnS alloy quantum dots by a hydrothermal method Reviewed

    H. Nishimura, Y. Lin, M. Hizume, T. Taniguchi, N. Shigekawa, T. Takagi, S. Sobue, S. Kawai, E. Okuno, D. Kim

    Chemistry Letters   48   1081 - 1083   2019.09

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  • Effects of Layered Cadmium-Based Nanoparticles on Si Solar Cells

    Idutsu Y.

    Conference Record of the IEEE Photovoltaic Specialists Conference   1753 - 1755   2019.06( ISSN:01608371 ( ISBN:9781728104942

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  • Temperature dependence of photoluminescence properties of water-soluble ZnSe quantum dots

    Lee Y.S.

    Journal of Physics: Conference Series   1220 ( 1 )   2019.05( ISSN:17426588

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  • Absorption and photoluminescence properties of CdSe quantum dots prepared by hydrothermal method

    Lee T.

    Journal of Physics: Conference Series   1220 ( 1 )   2019.05( ISSN:17426588

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  • Preparation of ZnSe-ZnS alloy quantum dots by a hydrothermal method and their optical properties

    Nishimura H.

    Journal of Physics: Conference Series   1220 ( 1 )   2019.05( ISSN:17426588

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  • Temperature dependence of photoluminescence properties of water-soluble CdS quantum dots

    Shimura K.

    Journal of Physics: Conference Series   1220 ( 1 )   2019.05( ISSN:17426588

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  • Hydrothermal synthesis of ZnSe:Mn quantum dots and their optical properties

    Nishimura H.

    AIP Advances   9 ( 2 )   2019.02

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  • Hydrothermal synthesis of ZnSe:Mn quantum dots and their optical properties Reviewed

    Hisaaki Nishimura, Yuxin Lin, Masayuki Hizume, Taichi Taniguchi, Naoteru Shigekawa, Tomomi Takagi, Susumu Sobue, Shoichi Kawai, Eiichi Okuno, and DaeGwi Kim

    AIP Advances   2019.02

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    Publishing type:Research paper (scientific journal)   Kind of work:Joint Work  

  • Hydrothermal synthesis of ZnSe:Mn quantum dots and their optical properties Reviewed

    Hisaaki Nishimura, Yuxin Lin, Masayuki Hizume, Taichi Taniguchi, Naoteru Shigekawa, Tomomi Takagi, Susumu Sobue, Shoichi Kawai, Eiichi Okuno, DaeGwi Kim

    AIP Advances   2019.02

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  • Correlated Roles of Temperature and Dimensionality for Multiple Exciton Generation and Electronic Structures in Quantum Dot Superlattices

    Chang I-Ya, Kim DaeGwi, Kim Hyeon-Deuk

    123 ( 4 )   2549 - 2556   2019.01( ISSN:19327447

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    Quantum dot superlattices (QDSLs), which are one-, two-, and three-dimensional periodic superlattices composed of QDs, induce dimensionality dependent quantum resonance among component QDs and thus represent a new type of condensed matter exhibiting novel energy, exciton, and carrier dynamics. We focused on the two important parameters, dimensionality and temperature, and identified their correlated roles to determine the electronic and photoexcited properties intrinsic to each QDSL at each dimensionality and temperature. We computationally demonstrated that the multiple exciton generation is significantly accelerated at higher temperature especially in the higher-dimensional QDSLs, indicating their great advantage especially at ambient temperature compared to an isolated zero-dimensional QD. Both dimensionality and temperature can be crucial and correlated parameters for independent tailoring of the properties of the QDSLs without changing the size, shape, and compositions of component QDs. The physical insights and advantage of the QDSLs we found here will lead to designing efficient and space-saving optoelectronic and photovoltaic devices that work at ambient temperature.

    DOI: 10.1021/acs.jpcc.8b10565

    CiNii Article

  • Absence of delayed fluorescence and triplet-triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes Reviewed

    2. Yong-Jin Pu, Rei Satake, Yuki Koyama, Takahiro Otomo, Rika Hayashi, Naoki Haruta, Hiroshi Katagiri, Daisuke Otsuki, DaeGwi Kim, and Tohru Sato

    Journal of Material Chemistry C   2019

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  • Correlated Roles of Temperature and Dimensionality for the Multiple Exciton Generation and Electronic Structures in the Quantum Dot Superlattices Reviewed

    I-Ya Chang, DaeGwi Kim, and Kim Hyeon-Deuk

    Journal of Physical Chemistry C   123   2549 - 2556   2019

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  • Temperature dependence of photoluminescence properties of water-soluble ZnSe quantum dots Reviewed

    Yong-Shin Lee, Taichi Taniguchi, and DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Temperature dependence of photoluminescence properties of water-soluble CdS quantum dots Reviewed

    Kunio Shimura, TaeGi Lee, and DaeGwi Kim

    Journal of Physics: Conference Series   2019

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    Publishing type:Research paper (scientific journal)   Kind of work:Joint Work  

  • Preparation of ZnSe-ZnS alloy quantum dots by a hydrothermal method and their optical properties Reviewed

    Hisaaki Nishimura, Yuxin Lin, Yuuki Kunimasa, and DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Absorption and photoluminescence properties of CdSe quantum dots prepared by hydrothermal method Reviewed

    TaeGi Lee, Kaito Noguchi, Hisaaki Nishimura, and DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Synthesis of water-soluble CuInS2 quantum dots by a hydrothermal method and their optical properties Reviewed

    Kazutaka Iida, Yota Uehigashi, Hideki Ichida, Hang-Beom Bu, and DaeGwi Kim

    Bulletin of the Chemical Society of Japan   2019

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  • Surface modification effects on defect-related photoluminescence in colloidal CdS quantum dots

    Lee Taegi, Shimura K., Kim D.

    Meeting Abstracts of the Physical Society of Japan   74.1 ( 0 )   1599 - 1599   2019

  • Absorption and photoluminescence properties of CdSe quantum dots prepared by hydrothermal method Reviewed

    TaeGi Lee, Kaito Noguchi, Hisaaki Nishimura, DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Absence of delayed fluorescence and triplet-triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes

    Pu Y.J.

    Journal of Materials Chemistry C   7 ( 9 )   2541 - 2547   2019( ISSN:20507534

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  • Absence of delayed fluorescence and triplet-triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes Reviewed

    Yong-Jin Pu, Rei Satake, Yuki Koyama, Takahiro Otomo, Rika Hayashi, Naoki Haruta, Hiroshi Katagiri, Daisuke Otsuki, DaeGwi Kim, Tohru Sato

    Journal of Material Chemistry C   2019

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  • Photoluminescence on/off switching of CdSe/ZnS core/shell quantum dots coated with diarylethene ligands

    Seto Y.

    Chemistry Letters   48 ( 11 )   1394 - 1397   2019( ISSN:03667022

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  • Preparation of ZnSe-ZnS alloy quantum dots by a hydrothermal method and their optical properties Reviewed

    Hisaaki Nishimura, Yuxin Lin, Yuuki Kunimasa, DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Synthesis of Mn-doped ZnSe-ZnS alloy quantum dots by a hydrothermal method

    Nishimura H.

    Chemistry Letters   48 ( 9 )   1081 - 1083   2019( ISSN:03667022

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  • Synthesis of water-soluble CuInS2 quantum dots by a hydrothermal method and their optical properties Reviewed

    Kazutaka Iida, Yota Uehigashi, Hideki Ichida, Hang-Beom Bu, DaeGwi Kim

    Bulletin of the Chemical Society of Japan   2019

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  • Synthesis of water-soluble CuInS<inf>2</inf> quantum dots by a hydrothermal method and their optical properties

    Iida K.

    Bulletin of the Chemical Society of Japan   92 ( 5 )   930 - 936   2019( ISSN:00092673

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  • Temperature dependence of photoluminescence properties of water-soluble CdS quantum dots Reviewed

    Kunio Shimura, TaeGi Lee, DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Temperature dependence of photoluminescence properties of water-soluble ZnSe quantum dots Reviewed

    Yong-Shin Lee, Taichi Taniguchi, DaeGwi Kim

    Journal of Physics: Conference Series   2019

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  • Correlated Roles of Temperature and Dimensionality for the Multiple Exciton Generation and Electronic Structures in the Quantum Dot Superlattices Reviewed

    I-Ya Chang, DaeGwi Kim, Kim Hyeon-Deuk

    Journal of Physical Chemistry C   123   2549 - 2556   2019

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  • Experimental verification of Förster energy transfer and quantum resonance between semiconductor quantum dots Reviewed

    DaeGwi Kim, Taegi Lee, Yong-Shin Lee, and Taichi Watanabe

    Current Applied Physics   18   S14 - S20   2018.08

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    Publishing type:Research paper (scientific journal)   Kind of work:Single Work  

  • Experimental verification of Förster energy transfer and quantum resonance between semiconductor quantum dots Reviewed

    DaeGwi Kim, TaeGi Lee, Yong-Shin Lee, Taichi Watanabe

    Current Applied Physics   18   S14 - S20   2018.08( ISSN:1567-1739

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    Quantum dot (QD) superlattices have the potential to provide new optical properties and functions based on interactions between adjacent QDs. Two types of interactions occur between the QDs: energy transfer (ET) from small-sized QDs to large QDs and resonant coupling between QDs with equal eigenenergies. Since ET and resonant coupling strongly depend on the distance between QDs, it is critical to precisely control the distance to understand the interaction mechanism. In this review, we describe that the distance between QDs can be controlled with an accuracy of 1 nm by a layer-by-layer method and further explain the mechanisms of ET and resonant coupling between adjacent QDs.

    DOI: 10.1016/j.cap.2017.11.012

  • Surface modification effects on defect-related photoluminescence in colloidal CdS quantum dots Reviewed

    Taegi Lee, Kuni Shimura, and DaeGwi Kim

    Physical Chemistry Chemical Physics   20   11954 - 11958   2018.04

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  • Optical properties of CdTe quantum dot superlattices self-organized by electrostatic interaction II

    Lee Yong-Shin, Watanabe Taichi, Kim DaeGwi

    Meeting Abstracts of the Physical Society of Japan   73.1 ( 0 )   1413 - 1413   2018

  • Quick synthesis of water-soluble, luminescent ZnTe nanoparticles by hydrothermal technique Reviewed

    Hang-Beom Bu, DaeGwi Kim

    Chemistry Letters   47 ( 2 )   152 - 155   2018( ISSN:1348-0715

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    We first report the successful quick synthesis of watersoluble ZnTe nanoparticles (NPs) by a hydrothermal technique. The use of N-acetyl-L-cysteine as a ligand and adjustment of the precursor solution pH to 10.3 ± 0.2 are believed to play key roles in the quick synthesis of ZnTe NPs with a high photoluminescence quantum efficiency of 15%. The reaction time is at least 140-fold quicker than previous work. The results surely indicate the potential of NPs in biomedical applications as a novel type of fluorescent nanoprobe.

    DOI: 10.1246/cl.170917

  • Surface modification effects on defect-related photoluminescence in colloidal CdS quantum dots Reviewed

    Taegi Lee, Kunio Shimura, Daegwi Kim

    Physical Chemistry Chemical Physics   20 ( 17 )   11954 - 11958   2018( ISSN:1463-9076

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    We investigated the effects of surface modification on the defect-related photoluminescence (PL) band in colloidal CdS quantum dots (QDs). A size-selective photoetching process and a surface modification technique with a Cd(OH)2 layer enabled the preparation of size-controlled CdS QDs with high PL efficiency. The Stokes shift of the defect-related PL band before and after the surface modification was ∼1.0 eV and ∼0.63 eV, respectively. This difference in the Stokes shifts suggests that the origin of the defect-related PL band was changed by the surface modification. Analysis by X-ray photoelectron spectroscopy revealed that the surface of the CdS QDs before and after the surface modification was S rich and Cd rich, respectively. These results suggest that Cd-vacancy acceptors and S-vacancy donors affect PL processes in CdS QDs before and after the surface modification, respectively.

    DOI: 10.1039/c7cp07812a

  • Quick synthesis of water-soluble, luminescent ZnTe nanoparticles by hydrothermal technique Reviewed

    H. Bu and D. Kim

    Chem. Lett.   47   152 - 155   2017.11

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  • Control of multiple exciton generation and electron-phonon coupling by interior nano space in hyper-structured quantum dot superlattice Reviewed

    I. Chang, D. Kim, and H. Kim

    ACS Appl. Mater. Interfaces   9   32080 - 32088   2017.08

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  • Synthesis of Mn<sup>2+</sup> doped ZnSe quantum dots using core/shell structures

    Nishimura Hisaaki, Maekawa Takaya, Takagi Tomomi, Sobue Susumu, Kawai Syouichi, Hasegawa Jyun, Kim DaeGwi

    JSAP Annual Meetings Extended Abstracts   2017.2 ( 0 )   1876 - 1876   2017.08

  • Control of multiple exciton generation and electron-phonon coupling by interior nano space in hyper-structured quantum dot superlattice Reviewed

    I. Chang, D. Kim, H. Kim

    ACS Appl. Mater. Interfaces   9   32080 - 32088   2017.08

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  • Influence of carrier localization at the core/shell interface on the temperature dependence of the Stokes shift and the photoluminescence decay time in CdTe/CdS type-II quantum dots Reviewed

    T. Watanabe, K. Takahashi, K. Shimura, and D. Kim

    Phys. Rev. B   96   035305-1 - 035305-7   2017.07

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  • Influence of carrier localization at the core/shell interface on the temperature dependence of the Stokes shift and the photoluminescence decay time in CdTe/CdS type-II quantum dots Reviewed

    Taichi Watanabe, Kohji Takahashi, Kunio Shimura, DaeGwi Kim

    PHYSICAL REVIEW B   96 ( 3 )   035305-1 - 035305-7   2017.07( ISSN:2469-9950

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    We have systematically investigated the temperature dependence of absorption, photoluminescence (PL), and PL decay profiles in CdTe-core and CdTe/CdS type-II quantum dots (QDs). In CdTe/CdS QDs, Stokes shifts and PL decay time become larger with an increase in temperature above 120 K, while those in CdTe-core QDs are almost independent of temperature. The unusual temperature dependence of Stokes shifts and PL decay time in CdTe/CdS QDs is understood by considering carrier localization at the core/shell interface at low temperatures and thermal-energy-assisted detrapping from localized-exciton to type-II exciton states at higher temperatures. Furthermore, a phenomenological rate-equation model is developed to explain the experimentally observed temperature-dependent PL decay time.

    DOI: 10.1103/PhysRevB.96.035305

  • Microwave-assisted hydrothermal synthesis of highly luminescent ZnSe-based quantum dots with a quantum yield higher than 90% Reviewed

    Y-S. Lee, K. Nakano, H-B. Bu, and D. Kim

    Appl. Phys. Express   10   065001-1 - 065001-4   2017.05

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  • Microwave-assisted hydrothermal synthesis of highly luminescent ZnSe-based quantum dots with a quantum yield higher than 90% Reviewed

    Y-S. Lee, K. Nakano, H-B. Bu, D. Kim

    Appl. Phys. Express   10   065001-1 - 065001-4   2017.05

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    Publishing type:Research paper (scientific journal)  

  • Optical properties of ZnSe quantum dots prepared by a hydrothermal method

    Lee Yong-Shin, Nakano Kaoru, Kim DaeGwi

    Meeting Abstracts of the Physical Society of Japan   72.1 ( 0 )   1511 - 1511   2017

  • Optical properties of CuInS<sub>2</sub> and CuInS<sub>2</sub>/ZnS quantum dots prepared by a hydrothermal method

    Umetsu Y., Nakatani T., Iida K., Kim D.

    Meeting Abstracts of the Physical Society of Japan   72.1 ( 0 )   1596 - 1596   2017

  • Synthesis of type-I CdTe core and type-II CdTe/CdS core/shell quantum dots by a hydrothermal method and their optical properties Reviewed

    Taichi Watanabe, Kohji Takahashi, Kunio Shimura, Hang-Beom Bu, Kim Hyeon-Deuk, Daegwi Kim

    Bulletin of the Chemical Society of Japan   90 ( 1 )   52 - 58   2017( ISSN:1348-0634

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    The breakthrough in high quality quantum dot (QD) synthesis has led to a great increase of QD studies and opened up possibilities for various applications, e.g., as light-emitting devices, biomolecular imaging,and photovoltaic devices. CdTe and CdTe/CdS QD were prepared via hydrothermal method in one-step processes by controlling reaction time. A gradual thermal decomposition of thiol ligand N-acetyl-L-cysteine led to the formation of a CdS shell on a CdTe core. X-ray diffraction and energy dispersive X-ray spectroscopy demonstrated that growth of the CdS shell started in a longer reaction time than 30 min and that the thickness of the CdS shell increased with increasing the reaction time. The CdTe/CdS QD displayed a longer photoluminescence-decay time than the CdTe core QD due to the type-II band alignment, and the decay time in the CdTe/CdS QD increased with an increase in the reaction time. The increase in the decay time in the CdTe/CdS QDs was qualitatively reproduced by a decrease in an overlap integral of electron and hole wave functions caused by an increase of the CdS shell thickness.

    DOI: 10.1246/bcsj.20160299

  • Temperature dependence of optical properties in CdTe/CdS type II quantum dots

    Watanabe T., Kim D.

    Meeting Abstracts of the Physical Society of Japan   72.1 ( 0 )   1510 - 1510   2017

  • Optical properties of CdTe quantum dot superlattices deposited by a layer-by-layer assembly

    Lee T., Ohshiro K., Watanabe T., Kim D.

    Meeting Abstracts of the Physical Society of Japan   72.1 ( 0 )   1512 - 1512   2017

  • Synthesis of type-I CdTe core and type-II CdTe/CdS core/shell quantum dots by a hydrothermal method and their optical properties Reviewed

    T. Watanabe, K. Takahashi, K. Shimura, H. Bu, H. Kim, and D. Kim

    Bull. Chem. Soc. Jpn.   90   52 - 58   2016.10

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  • Hydrothermal synthesis of wavelength conversion nanoparticles of ZnSe:Mn/ZnS

    Takagi Tomomi, Taniguchi Taichi, Sobue Susumu, Kawai Shoichi, Hasegawa Jun, DaeGwi Kim

    JSAP Annual Meetings Extended Abstracts   2016.2 ( 0 )   2948 - 2948   2016.09

  • Controls of electronic structures and phonon dynamics in quantum dot superlattice by manipulating interior nano space Reviewed

    I. Chang, D. Kim, and H. Kim

    ACS Appl. Mater. Interfaces   8   18321 - 18327   2016.07

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  • Control of Electronic Structures and Phonon Dynamics in Quantum Dot Superlattices by Manipulation of Interior Nanospace Reviewed

    I-Ya Chang, DaeGwi Kim, Kim Hyeon-Deuk

    ACS APPLIED MATERIALS & INTERFACES   8 ( 28 )   18321 - 18327   2016.07( ISSN:1944-8244

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    Quantum dot (QD) superlattices, periodically ordered array structures of QDs, are expected to provide novel photo-optical functions due to their resonant couplings between adjacent QDs. Here, we computationally demonstrated that electronic structures and phonon dynamics of a QD superlattice can be effectively and selectively controlled by manipulating its interior nanospace, where quantum resonance between neighboring QDs appears, rather than by changing component QD size, shape, compositions, etc. A simple Hpassivated Si QD was examined to constitute one-, two-, and three-dimensional QD superlattices, and thermally fluctuating band energies and phonon modes were simulated by finite-temperature ab initio molecular dynamics (MD) simulations. The QD superlattice exhibited a decrease in the band gap energy enhanced by thermal modulations and also exhibited selective extraction of charge carriers out of the component QD, indicating its advantage as a promising platform for implementation in solar cells. Our dynamical phonon analyses based on the ab initio MD simulations revealed that THz-frequency phonon modes were created by an inter-QD crystalline lattice formed in the QD superlattice, which can contribute to low energy thermoelectric conversion and will be useful for direct observation of the dimension-dependent superlattice. Further, we found that crystalline and ligand-originated phonon modes inside each component QD can be independently controlled by asymmetry of the superlattice and by restriction of the interior nanospace, respectively. Taking into account the thermal effects at the finite temperature, we proposed guiding principles for designing efficient and space-saving QD superlattices to develop functional photovoltaic and thermoelectric devices.

    DOI: 10.1021/acsami.6b03219

  • Hydrothermal synthesis of NAC-capped II-VI semiconductor ZnSe quantum dots in acidic condition Reviewed

    Y-S. Lee, H. Bu, T. Taniguchi, T. Takagi, S. Sobue, H. Yamada, T. Iwaki, and D. Kim

    Chem. Lett.   45   878 - 880   2016.05

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  • Blueshifted flat dispersion relation of exciton-polariton condensates in a CuBr microcavity Reviewed

    M. Nakayama, K. Murakami, and D. Kim

    J. Phys. Soc. Jpn.   85   054702-1 - 054702-7   2016.04

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  • Blueshifted flat dispersion relation of exciton-polariton condensates in a CuBr microcavity Reviewed

    M. Nakayama, K. Murakami, D. Kim

    J. Phys. Soc. Jpn.   85   054702-1 - 054702-7   2016.04

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  • Control of photoluminescence intensity in nanostructured layers of lipid-soluble quantum dots and water-soluble gold nanoparticles Reviewed

    K. Ohshiro, H. Bu, and D. Kim

    Chem. Lett.   45   520 - 522   2016.02

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  • Optical properties of CdTe quantum dot superlattices self-organized by electrostatic interaction

    Lee Yong-Shin, Watanabe Taichi, Takahashi Kohji, Kim DaeGwi

    Meeting Abstracts of the Physical Society of Japan   71.2 ( 0 )   1362 - 1362   2016

  • Energy transfer in layered structures composed of different semiconductor quantum dots

    Asakawa Ryousuke, Kim DaeGwi

    Meeting Abstracts of the Physical Society of Japan   71.2 ( 0 )   1361 - 1361   2016

  • Control of photoluminescence intensity in nanostructured layers of lipid-soluble quantum dots and water-soluble gold nanoparticles Reviewed

    Kazuma Ohshiro, Hang-Beom Bu, DaeGwi Kim

    Chemistry Letters   45 ( 5 )   520 - 522   2016( ISSN:1348-0715

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    We propose a new preparation method for layered structures consisting of lipid-soluble CdSe quantum dots (QDs) and watersoluble Au nanoparticles (NPs). The self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (MPTMS) was introduced as a "binder" of lipid-soluble QDs on a polyelectrolyte layer (PE). Furthermore, the separation distance between the CdSe QDs and the Au NP layers was controlled by the thickness of the PE layers, and the systematic change from PL quenching to PL enhancement of the CdSe QDs is observed.

    DOI: 10.1246/cl.160096

  • Hydrothermal synthesis of NAC-capped II-VI semiconductor ZnSe quantum dots in acidic condition Reviewed

    Yong-Shin Lee, Hang-Beom Bu, Taichi Taniguchi, Tomomi Takagi, Susumu Sobue, Hitoshi Yamada, Takao Iwaki, Daegwi Kim

    Chemistry Letters   45 ( 8 )   878 - 880   2016( ISSN:1348-0715

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    Semiconductor ZnSe quantum dots (QDs) were hydrothermally prepared by the reaction of Zn2+ and NaHSe in the presence of N-acetyl-L-cysteine as a stabilizer. The absorption bandwidth depends strongly on the pH of the working solutions. The photoluminescence (PL) properties were dramatically improved by selecting appropriately the pH value of the precursor solution
    the PL intensity in the ZnSe QDs prepared at pH 6 was strongest irrespective of the size of ZnSe QDs. The XRD pattern demonstrated the formation of a cubic zinc blende ZnSe lattice structure and crystallinity.

    DOI: 10.1246/cl.160431

  • Control of localized surface plasmon resonance energy in monolayer structures of gold and silver nanoparticles Reviewed

    H. Yokota, T. Taniguchi, T. Watanabe, and D. Kim

    Phys. Chem. Chem. Phys.   17   27077 - 27081   2015.09

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  • Theory of the lifetime of an exciton incoherently created below its resonance frequency by inelastic scattering Reviewed

    M. Bamba, S. Wakaiki, H. Ichida, K. Mizoguchi, D. Kim, M. Nakayama, and Y. Kanematsu

    Phys. Rev. B   91   235205-1 - 235205-13   2015.06

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  • Evidence of quantum resonance in periodically-ordered three-dimensional superlattice of CdTe quantum dots Reviewed

    D. Kim, S. Tomita, K. Ohshiro, T. Watanabe, T. Sakai, I. Chang, and H. Kim

    Nano Letters   15   4343 - 4347   2015.06

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  • Evidence of quantum resonance in periodically-ordered three-dimensional superlattice of CdTe quantum dots Reviewed

    D. Kim, S. Tomita, K. Ohshiro, T. Watanabe, T. Sakai, I. Chang, H. Kim

    Nano Letters   15   4343 - 4347   2015.06

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  • Polariton-condensation effects on photoluminescence properties in a CuBr microcavity Reviewed

    M. Nakayama, K. Murakami, Y. Furukawa, and D. Kim

    J. Physics: Conf. Series   619   012015-1 - 012015-4   2015.05

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  • Effects of surface modification on photoluminescence properties of self-assembled monolayer of CdSe quantum dots Reviewed

    T. Watanabe, H. Yokota, M. Nakayama, and D. Kim

    J. Physics: Conf. Series   619   012024-1 - 012024-4   2015.05

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  • Polariton-condensation effects on photoluminescence properties in a CuBr microcavity Reviewed

    M. Nakayama, K. Murakami, Y. Furukawa, D. Kim

    J. Physics: Conf. Series   619   012015-1 - 012015-4   2015.05

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  • Effects of surface modification on photoluminescence properties of self-assembled monolayer of CdSe quantum dots Reviewed

    T. Watanabe, H. Yokota, M. Nakayama, D. Kim

    J. Physics: Conf. Series   619   012024-1 - 012024-4   2015.05

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  • Preparation of highly luminescent hybrid gel incorporating NAC-capped CdTe quantum dots through sol–gel processing Reviewed

    H Bu, T. Watanabe, M. Hizume, T. Takagi, S. Sobue, S. Kawai, E. Okuno, and D. Kim

    Mater. Res. Express   2   036202-1 - 036202-9   2015.03

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  • Preparation of highly luminescent hybrid gel incorporating NAC-capped CdTe quantum dots through sol-gel processing Reviewed

    Hang-Beom Bu, Taichi Watanabe, Masayuki Hizume, Tomomi Takagi, Susumu Sobue, Shoichi Kawai, Eiichi Okuno, DaeGwi Kim

    MATERIALS RESEARCH EXPRESS   2 ( 3 )   036202-1 - 036202-9   2015.03( ISSN:2053-1591

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    Highly photoluminescent gel was prepared by embedding water soluble quantum dots (QDs) in an inorganic-organic hybrid gel matrix using a conventional sol-gel process. Aminopropyltrimethoxysilane and citric acid (CA) were found to be the best combination for the gel preparation. C-13-NMR and FT-IR studies indicated hydrogen bond formation between the amine group of APS and the carboxyl group of CA. IR-light radiation curing was comparable to thermal curing and reduced the gelation time to a considerable extent (71%). The resulting composite formed a hybrid gel phosphor with excellent transparency by embedding CdTe QDs into the matrix and emitted light of various colors with high photoluminescence efficiency (40%). The gel phosphor retained the PL properties after storage in air for one year. In addition, the strength of the hybrid phosphor was demonstrated by a coin-flipping test.

    DOI: 10.1088/2053-1591/2/3/036202

  • 17aCE-5 Diffusive Goldstone mode under polariton condensation in a CuBr microcavity

    Nakayama Masaaki, Murakami Katsuya, Kim DaeGwi

    Meeting Abstracts of the Physical Society of Japan   70.2 ( 0 )   1195   2015

  • 23pPSA-43 Optical properties of CuInS_2 quantum dots prepared by a hydrothermal method

    Iida K., Yokota H., Bu H., Kim D.

    Meeting Abstracts of the Physical Society of Japan   70.1 ( 0 )   1588   2015

  • 23pPSA-42 Optical properties of layered structures of CdSe quantum dots

    Oshiro K., Hizume M., Yokota H., Kim D.

    Meeting Abstracts of the Physical Society of Japan   70.1 ( 0 )   1587   2015

  • 23pPSA-41 Temperature dependence of energy transfer dynamics between CdTe quantum dots

    Ito T., Watanabe T., Kim D.

    Meeting Abstracts of the Physical Society of Japan   70.1 ( 0 )   1586   2015

  • Control of localized surface plasmon resonance energy in monolayer structures of gold and silver nanoparticles Reviewed

    Hiroki Yokota, Taichi Taniguchi, Taichi Watanabe, DaeGwi Kim

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   17 ( 40 )   27077 - 27081   2015( ISSN:1463-9076

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    Monolayer structures of Au and Ag nanoparticles (NPs) were fabricated by a dipping method to realize the control of localized surface plasmon resonance (LSPR) energy. The mean inter-particle distance in the monolayer was controlled by changing the concentration of NPs in the colloidal solution used for the monolayer assembly. The extinction-peak energy of the monolayer structure was red-shifted with decreasing inter-particle distance, reflecting plasmon coupling between NPs.

    DOI: 10.1039/c5cp03928b

  • Hydrothermal synthesis of N-acetyl-L-cysteine-capped CuInS2 nanoparticles Reviewed

    Hang-Beom Bu, Hiroki Yokota, Kunio Shimura, Kohji Takahasi, Taichi Taniguchi, DaeGwi Kim

    Chemistry Letters   44 ( 2 )   200 - 202   2015( ISSN:1348-0715

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    CuInS2 (CIS) nanoparticles (NPs) were hydrothermally prepared by the reaction of Cu2+, In2+, and Na2S in the presence of N-acetyl-L-cysteine as a stabilizer. The X-ray diffraction pattern of the resultant CIS NPs indicated that the chalcopyrite NPs could be obtained. The X-ray photoelectron spectroscopy data suggested that Cu2+ is reduced to Cu+ during the reaction process. The absorption and photoluminescence peaks of the NPs were clearly red-shifted with increasing size of the particles. Our method will aid in the synthesis of other I-III-VI ternary compounds.

    DOI: 10.1246/cl.140950

  • Hydrothermal Synthesis of N-Acetyl-L-cysteine-capped CuInS2 Nanoparticles Reviewed

    H. Bu, H. Yokota, K. Shimura, K. Takahasi, T. Taniguchi, and D. Kim

    Chem. Lett.   44   200 - 202   2014.11

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  • Hydrothermal synthesis of wavelength conversion nanoparticles of ZnSeS:Mn

    Takagi Tomomi, Taniguchi Taichi, Sobue Susumu, Kawai Shoichi, Okuno Eiichi, Hasegawa Jun, Kim DaeGwi

    JSAP Annual Meetings Extended Abstracts   2014.2 ( 0 )   497 - 497   2014.09

  • Photoluminescence characteristics of polariton condensation in a CuBr microcavity Reviewed

    M. Nakayama, K. Murakami, Y. Furukawa, and D. Kim

    Appl. Phys. Lett.   105   021903-1 - 021903-4   2014.07

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  • Photoluminescence characteristics of polariton condensation in a CuBr microcavity Reviewed

    Masaaki Nakayama, Katsuya Murakami, Yoshiaki Furukawa, DaeGwi Kim

    APPLIED PHYSICS LETTERS   105 ( 2 )   021903-1 - 021903-4   2014.07( ISSN:0003-6951

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    We have investigated the photoluminescence (PL) properties of a CuBr microcavity at 10 K, including the temporal profiles, from the viewpoint of cavity-polariton condensation. The excitation energy density dependence of the PL intensity (band width) of the lower polariton branch at an in-plane wave vector of k(parallel to)=0 exhibits a threshold-like increase (decrease). A large blueshift in the PL energy of similar to 10 meV caused by the cavity-polariton renormalization is correlated with the excitation energy density dependence of the PL intensity. The estimated density of photogenerated electron-hole pairs at the threshold is two orders lower than the Mott transition density. These results consistently demonstrate the occurrence of cavity-polariton condensation. In addition, we found that the PL rise and decay times are shortened dramatically by the cavity-polariton condensation, which reflects the bosonic final state stimulation in the relaxation process and the intrinsic cavity-polariton lifetime in the decay process. (C) 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4890216

  • High-sensitivity polarization modulation reflectance spectroscopy of cavity polaritons in a ZnO microcavity

    Takayuki Hasegawa, Ryo Kishimoto, Yoshihiro Takagi, Toshiki Kawase, DaeGwi Kim, Masaaki Nakayama

    APPLIED PHYSICS EXPRESS   7 ( 3 )   032003 (4 pages)   2014.03( ISSN:1882-0778

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    We report that polarization modulation reflectance (PMR) spectroscopy is highly sensitive to the cavity polaritons in a ZnO microcavity with HfO2/SiO2 distributed Bragg reflectors. We demonstrate that the cavity-polariton dispersion, even in the energy region of strong absorption by exciton continuum states, is clearly observed by PMR spectroscopy. The PMR spectra were quantitatively analyzed by a transfer-matrix method taking into account three types of excitons labeled A, B, and C. Line-shape analysis of the PMR spectra indicates that the anisotropy of the excitonic transitions is considerable in treating the cavity polariton in the ZnO microcavity. (C) 2014 The Japan Society of Applied Physics

    DOI: 10.7567/APEX.7.032003

  • Observation of bound and antibound states of cavity polariton pairs in a CuCl microcavity

    S. Matsuura, Y. Mitsumori, H. Kosaka, K. Edamatsu, K. Miyazaki, D. Kim et al.

    Phys. Rev. B   89   035317 (6 pages)   2014

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  • High-sensitivity polarization modulation reflectance spectroscopy of cavity polaritons in a ZnO microcavity

    T. Hasegawa, R. Kishimoto, Y. Takagi, T. Kawase, D. Kim, and M. Nakayama

    App. Phys. Exp.   7   032003 (4 pages)   2014

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  • 8aAJ-4 Polariton-condensation effects on photoluminescence properties in a CuBr microcavity

    Murakami Katsuya, Furukawa Yoshiaki, Kim DaeGwi, Nakayama Masaaki

    Meeting Abstracts of the Physical Society of Japan   69.2.4 ( 0 )   514   2014

  • 29pPSA-22 Optical properties of CdTe quantum dot multilayers prepared by layer-by-layer assembly II

    Tomita S., Watanabe T., Takahashi K., Nakayama M., Kim D.

    Meeting Abstracts of the Physical Society of Japan   69.1.4 ( 0 )   765   2014

  • 10aPS-33 Temperature dependence of optical properties of CdTe quantum dots prepared by a colloidal method

    Watanabe T., Ichida H., Takahashi K., Shimura K., Nakayama M., Kim D.

    Meeting Abstracts of the Physical Society of Japan   69.2.4 ( 0 )   543   2014

  • Observation of bound and antibound states of cavity polariton pairs in a CuCl microcavity

    S. Matsuura, Y. Mitsumori, H. Kosaka, K. Edamatsu, K. Miyazaki, D. Kim

    Phys. Rev. B   89   035317 (6 pages)   2014

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  • Precise control of photoluminescence enhancement and quenching of semiconductor quantum dots using localized surface plasmons in metal nanoparticles

    Daegwi Kim, Hiroki Yokota, Taichi Taniguchi, Masaaki Nakayama

    Journal of Applied Physics   114 ( 15 )   154307 (5 pages)   2013.10( ISSN:0021-8979

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    Photoluminescence (PL) enhancement and quenching using localized surface plasmons in metal nanoparticles (NPs) are important factors to control optical properties of semiconductor quantum dots (QDs). However, the PL enhancement and quenching have not been simultaneously observed in previous works, which lead to the situation that the mechanisms for controlling the enhancement and quenching are still controversial. In this work, we have investigated the PL properties in bilayer structures consisting of Au NPs and CdSe QDs in order to realize the precise control of the PL enhancement and quenching of the QDs. It was demonstrated that both the separation distance between Au NPs and CdSe QDs and the surface density of Au NPs in the bilayer structure are key factors for controlling the balance between the PL enhancement and quenching. The experimental results were quantitatively analyzed, taking account of the energy transfer from CdSe QDs to Au NPs and local electric field effects due to Au NPs. © 2013 AIP Publishing LLC.

    DOI: 10.1063/1.4826188

  • Control of Rabi splitting energies of exciton polaritons in CuI microcavities

    M. Nakayama, M. Kameda, T. Kawase, and D. Kim

    Eur. Phys. J. B   86   32 (5pages)   2013

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  • Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties

    H. Bu, H. Kikunaga, K. Shimura, K. Takahasi, T. Taniguchi, and D. Kim

    Phys. Chem. Chem. Phys.   15   2903 - 2911   2013

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  • Photon-field-shape effects on Rabi splitting energies in CuCl microcavities

    T. Kawase, K. Miyazaki, D. Kim, M. Nakayama

    Eur. Phys. J. B   86   69 (6pages)   2013

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  • Thickness dependence of photoluminescence-decay profiles of exciton-exciton scattering in ZnO thin films

    S. Wakaiki, H. Ichida, T. Kawase, K. Mizoguchi, D. Kim, M. Nakayama, Y. Kanematsu

    Eur. Phys. J. B   86   387 (4pages)   2013

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  • Temperature dependence of photoluminescence dynamics of self-assembled monolayers of CdSe quantum dots: the influence of the bound-exciton state

    D. Kim, H. Yokota, K. Shimura, and M. Nakayama

    Phys. Chem. Chem. Phys.   15   21051 - 21057   2013

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  • Precise control of photoluminescence enhancement and quenching of semiconductor quantum dots using localized surface plasmons in metal nanoparticles

    D. Kim, H. Yokota, T. Taniguchi, and M. Nakayama

    J. Appl. Phys.   114   154307 (5 pages)   2013

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  • Thickness dependence of photoluminescence-decay profiles of exciton-exciton scattering in ZnO thin films

    S. Wakaiki, H. Ichida, T. Kawase, K. Mizoguchi, D. Kim, M. Nakayama, Y. Kanematsu

    Eur. Phys. J. B   86   387 (4pages)   2013

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  • 28pEH-1 Photon-field-shape effects on Rabi splitting energies in CuCl microcavities

    Kawakami M., Miyazaki K., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   68.1.4 ( 0 )   821   2013

  • 27pEJ-3 Optical properties of semicondctor quantum dots-metal nanoparticles bilayer structures II

    Taniguchi T., Yokota H., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   68.1.4 ( 0 )   812   2013

  • Optical properties of CdTe and CdTe/CdS quantum dots prepared by a hydrothermal method

    Watanabe T., Tomita S., Takahashi K., Shimura K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   68.2.4 ( 0 )   663   2013

  • Optical properties of CdTe quantum dot multilayers prepared by layer-by-layer assembly

    Tomita S., Watanabe T., Takahashi K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   68.2.4 ( 0 )   654   2013

  • Photon-field-shape effects on Rabi splitting energies in CuCl microcavities

    T. Kawase, K. Miyazaki, D. Kim, M. Nakayama

    Eur. Phys. J. B   86   69 (6pages)   2013

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  • Temperature dependence of photoluminescence dynamics of self-assembled monolayers of CdSe quantum dots: the influence of the bound-exciton state

    D. Kim, H. Yokota, K. Shimura, M. Nakayama

    Phys. Chem. Chem. Phys.   15   21051 - 21057   2013

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  • Control of Rabi splitting energies of exciton polaritons in CuI microcavities

    M. Nakayama, M. Kameda, T. Kawase, D. Kim

    Eur. Phys. J. B   86   32 (5pages)   2013

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  • Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties

    Hang-Beom Bu, Hayato Kikunaga, Kunio Shimura, Kohji Takahasi, Taichi Taniguchi, DaeGwi Kim

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   15 ( 8 )   2903 - 2911   2013( ISSN:1463-9076

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    Water soluble nanoparticles (NPs) with a high emission property were synthesized via hydrothermal routes. In this report, we chose thiol ligand N-acetyl-L-cysteine as the ideal stabilizer and have successfully employed it to synthesize readily size-controllable CdTe NPs in a reaction of only one step. Hydrothermal synthesis of CdTe NPs has been carried out in neutral or basic conditions so far. We found out that the pH value of precursor solutions plays an important role in the uniformity of the particle size. Actually, high quality CdTe NPs were synthesized under mild acidic conditions of pH 5. The resultant NPs indicated good visible light-emitting properties and stability. Further, the experimental results showed that the reaction temperature influenced significantly the growth rate and the maximum size of the NPs. The CdTe NPs with a high photoluminescence quantum yield (the highest value: 57%) and narrower half width at half maximum (the narrowest value: 33 nm) were attained in very short time, within 40 minutes, reaching diameters of 2.3 to 4.3 nm. The PL intensity was increased with an increase in the reaction time, reflecting the suppression of nonradiative recombination processes. Furthermore, the formation of CdTe/CdS core-shell structures was discussed from the viewpoint of PL dynamics and X-ray diffraction studies.

    DOI: 10.1039/c2cp43299d

  • Temperature dependence of cavity-polariton energies in ZnO and CuCl microcavities

    Toshiki Kawase, Kenichi Miyazaki, Daegwi Kim, Masaaki Nakayama

    JOURNAL OF APPLIED PHYSICS   112 ( 9 )   093512 (6 pages).   2012.11( ISSN:0021-8979

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    We have investigated the temperature dependence of the cavity-polariton energies in ZnO and CuCl microcavities with HfO2/SiO2 distributed Bragg reflectors. From angle-resolved reflectance spectra at 10 K, we experimentally confirmed the cavity-polariton dispersions. The experimental dispersions were analyzed with a phenomenological Hamiltonian for the exciton-photon strong coupling. Furthermore, the temperature dependence of the angle-resolved reflectance spectra was measured. We analyzed the experiment results of the temperature dependence of the energies of the cavity polaritons on the basis of the phenomenological Hamiltonian, taking account of Varshni's law to treat the temperature dependence of the band-gap energy in a bulk crystal. Note that the temperature dependence of the exciton energies in a CuCl bulk crystal is extraordinary, which is in reverse to that in a ZnO bulk crystal. We have revealed that the temperature dependence of the energies of the cavity polaritons, which deviates from that of the exciton in the bulk crystal, considerably depends on the relative fractions of the exciton and cavity-photon components in the cavity polaritons. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764327]

    DOI: 10.1063/1.4764327

  • Exciton polaritons in a CuBr microcavity with HfO2/SiO2 distributed Bragg reflectors

    M. Nakayama, Y. Kanatanai, T. Kawase, D. Kim

    PHYSICAL REVIEW B   85 ( 20 )   205320 (5 pages)   2012.05( ISSN:1098-0121

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    We have investigated the characteristics of exciton-photon strong coupling in a CuBr bulk microcavity that consists of a CuBr active layer with an effective thickness of lambda/2 and HfO2/SiO2 distributed Bragg reflectors: lambda corresponds to an effective resonant wavelength of the lowest-lying exciton. The CuBr crystal has three excitons labeled Z(f), Z(1,2), and Z(3) at the Gamma point, where the Z(f) exciton originates from a triplet state, which is peculiar to CuBr. Angle-resolved reflectance spectra measured at 10 K demonstrate the strong coupling behavior of the Z(f), Z(1,2), and Z(3) excitons and cavity photon, resulting in the formation of four cavity-polariton branches. Analyzing the cavity-polariton dispersion relations based on a phenomenological Hamiltonian for the strong coupling, we evaluated the vacuum Rabi-splitting energies of the Z(f), Z(1,2), and Z(3) excitons to be 31, 108, and 84 meV, respectively. These Rabi-splitting energies reflect the magnitudes of the oscillator strengths of the relevant excitons. Furthermore, we precisely measured angle-resolved photoluminescence (PL) spectra of the lower polariton branch under a weak excitation condition. In the bottleneck region, the population of the cavity polaritons is negligible, and the PL intensity at k = 0 is the highest. These facts suggest that the relaxation process of the cavity polaritons is not affected by a bottleneck effect.

    DOI: 10.1103/PhysRevB.85.205320

  • Photoluminescence Properties of Self-Assembled Monolayers Of CdSe and CdSe/ZnS Quantum Dots

    H. Yokota, K. Okazaki, K. Shimura, M. Nakayama, D. Kim

    JOURNAL OF PHYSICAL CHEMISTRY C   116 ( 9 )   5456 - 5459   2012.03( ISSN:1932-7447

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    The photoluminescence (PL) properties of self-assembled monolayers (SAMs) of CdSe and CdSe/ZnS quantum dots (QDs) were investigated. From measurements of the temperature dependence of PL spectra, it is demonstrated that the thiol group, which is a constituent of the reagent for formation of the SAM, degrades the PL properties during the SAM formation process. With an additional dipping treatment in a Cd(CIO4)(2) aqueous solution with pH = 10, the band-edge PL intensity is increased remarkably. The improvement of PL properties is attributed to QD surface modification with a Cd(OH)2 layer. On the other hand, the defect-related PL band is not observed at all, even at 10 K, in the SAMs of CdSe/ZnS core/shell QDs. This fact indicates that the ZnS shell layer prevents degradation of the PL properties during the SAM process.

    DOI: 10.1021/jp2116609

  • Polarization dependence of four wave mixing via biexcitons in CuCl microcavities

    S. Matsuura, Y. Mitsumori, H. Kosaka, K. Edamatsu, K. Miyazaki, Y. Kanatani, D. Kim et al.

    Phys. Status Solidi C   9   2505 - 2508   2012

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  • Photoluminescence properties of self-assembled monolayers of CdSe and CdSe/ZnS quantum dots

    H. Yokota, K. Okazaki, K. Shimura, M. Nakayama, and D. Kim

    J. Phys. Chem. C   116   5456 - 5459   2012

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  • Control of Rabi splitting energies in CuCl microcavities withHfO2/SiO2 distributed Bragg reflectors

    M. Nakayama, K. Miyazaki, T. Kawase, and D. Kim

    Physics Procedia   29   6 - 11   2012

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  • Exciton polaritons in a CuBr microcavity with HfO2/SiO2 distributed Bragg reflectors

    M. Nakayama, Y. Kanatanai, T. Kawase, and D. Kim

    Phys. Rev. B   85   205320 (5 pages)   2012

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  • Active-layer-thickness dependence of Rabi splitting energies in ZnO microcavities

    T. Kawase, D. Kim, and M. Nakayama

    Phys. Status Solidi C   9   1797 - 1800   2012

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  • Temperature dependence of cavity-polariton energies in ZnO and CuCl microcavities

    T. Kawase, K. Miyazaki, D. Kim, and M. Nakayama

    J. Appl. Phys.   112   093512 (6 pages).   2012

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  • Characteristics of cavity polaritons in a CuBr microcavity

    Y. Kanatani, T. Kawase, D. Kim, and M. Nakayama

    Eur. Phys. J. B   85   390 (6pages)   2012

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  • Optical properties of self-assembled monolayer of CdSe quantum dots

    H. Yokota, K. Shimura, M. Nakayama, and D. Kim

    Phys. Status Solidi C   9   2465 - 2468   2012

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  • Photoluminescence dynamics from exciton-exciton scattering and exciton-electron scattering in GaN thin film

    S. Wakaiki, H. Tokumaru, H. Ichida, K. Mizoguchi, D. Kim, Y. Kanematsu, and M. Nakayama

    Phys. Status Solidi C   9   2497 - 2500   2012

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  • Active-layer-thickness dependence of Rabi splitting energies in ZnO microcavities

    Toshiki Kawase, DaeGwi Kim, Masaaki Nakayama

    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 8-9   9 ( 8-9 )   1797 - 1800   2012( ISSN:1862-6351

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    We have investigated the active-layer-thickness dependence of Rabi splitting energies in ZnO microcavities. We fabricated ZnO microcavities using rf magnetron sputtering for the HfO2/SiO2 distributed Bragg reflector and pulsed-laser deposition for the ZnO active layer. In order to control of the Rabi splitting energies, the active layer thickness was changed from lambda/2 to 3 lambda/2. In angle-resolved reflectance spectra at 10 K, the cavity polaritons resulting from the strong coupling between A, B, and C excitons peculiar to ZnO and the cavity photon were clearly detected. We estimated the energies of the exciton-photon interaction, the so-called Rabi splitting energies, from the analysis of the cavity polariton dispersions using the phenomenological Hamiltonian for the strong exciton-photon coupling. The Rabi splitting energies markedly increase with an increase in the active layer thickness. The active-layer-thickness dependence of the Rabi splitting energies are explained by a semi-quantitatively analysis. Consequently, we have succeeded in the control of the Rabi splitting energies in the ZnO microcavities. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssc.201100583

  • 25aAC-6 Phntoluminescence properties of cavity polaritons in a CoBr microcavity

    Kanatani Y., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.1.4 ( 0 )   796   2012

  • 24pPSA-39 Optical properties of ZoSe qoanlum dots prepared by a colloidal method

    Taniguchi T., Kawasaki H., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.1.4 ( 0 )   782   2012

  • 20pFJ-6 Optical properties of CdTe quantum dots prepared by a colloidal method

    Tomita S., Takahashi K., Shimura K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.2.4 ( 0 )   707   2012

  • 20pFJ-5 Optical properties of layered structures of semiconductor quantum dots and metal nanoparticles

    Taniguchi T., Yokota H., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.2.4 ( 0 )   706   2012

  • 18pHB-8 Polariton lasing in a CuBr microcavity

    Kawase T., Kanatani Y., Ichida H., Wakaiki S., Kim D., Kanematsu Y., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.2.4 ( 0 )   674   2012

  • 18aPSB-3 Control of Rabi splitting energy in CuBr microcavities

    Kanatani Y., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   67.2.4 ( 0 )   659   2012

  • Photoluminescence dynamics originating from exciton-exciton and exciton-electron scattering in a GaN thin film

    Shuji Wakaiki, Hitoshi Tokumaru, Hideki Ichida, Kohji Mizoguchi, DaeGwi Kim, Yasuo Kanematsu, Masaaki Nakayama

    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 12   9 ( 12 )   2497 - 2500   2012( ISSN:1862-6351

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    We have investigated the photoluminescence (PL) dynamics of a GaN thin film under intense excitation conditions using an optical-Kerr-gating method. It has been found that the PL originating from the exciton-exciton scattering (P emission) appears at the temperatures lower than around 100 K, while at higher temperatures P emission vanishes and the PL originating from exciton-electron scattering (H emission) dominates. The ultrashort gating time of 0.6 ps enabled us to obtain precise information of the temporal profiles of the peak energy, the bandwidth, and the intensity of the P emission and H emission. We have found that the decay time of the H emission is shorter than that of the P emission. By taking into account the strong correlation between the decay time and the peak-energy position of the emissions, we conclude that the difference in the decay times is attributed to a change of the photon-like characteristics of the lower polariton branch that is the final state of the scattering process; namely, the photon-like component of the H emission is larger than that of the P emission. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssc.201200316

  • Polarization dependence of four-wave mixing via biexcitons in CuCl microcavities

    S. Matsuura, Y. Mitsumori, H. Kosaka, K. Edamatsu, K. Miyazaki, Y. Kanatani, D. Kim, M. Nakayama, G. Oohata, H. Oka, H. Ajiki, H. Ishihara

    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 12   9 ( 12 )   2505 - 2508   2012( ISSN:1862-6351

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    We studied the CuCl microcavity designed for the enhancement of the biexciton-photon coupling, in terms of spectrally resolved four-wave mixing. We observed the strong dependence of the spectrum on the polarization of the pump pulses and the polarization correlation between the pump pulses and the four-wave mixing signal, suggesting that the biexciton state is successfully formed in the CuCl microcavity. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssc.201200326

  • Characteristics of cavity polaritons in a CuBr microcavity

    Y. Kanatani, T. Kawase, D. Kim, M. Nakayama

    Eur. Phys. J. B   85   390 (6pages)   2012

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  • Optical properties of self-assembled monolayer of CdSe quantum dots

    Hiroki Yokota, Kunio Shimura, Masaaki Nakayama, DaeGwi Kim

    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 12   9 ( 12 )   2465 - 2468   2012( ISSN:1862-6351

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    The temperature dependence of absorption, photoluminescence (PL), and PL dynamics of self-assembled monolayers of CdSe quantum dots was investigated. The PL decay profiles become slower with an increase in temperature, contrary to an ordinary behaviour. We have revealed that such anomalous temperature dependence of the PL-decay profile below 200 K is explained by a four-state model consisting of a ground state, a bound-exciton state, and two free-exciton states of a lower-lying dark-exciton state and a higher-lying bright-exciton state. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssc.201200261

  • Control of Rabi splitting energies in CuCl microcavities with HfO2/SiO2 distributed Bragg reflectors

    M. Nakayama, K. Miyazaki, T. Kawase, D. Kim

    PROCEEDINGS OF THE 16TH INTERNATIONAL CONFERENCE ON LUMINESCENCE AND OPTICAL SPECTROSCOPY OF CONDENSED MATTER: POSTERS   29   6 - 11   2012( ISSN:1875-3892

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    The exciton-photon interaction in CuCl microcavities with HfO2/SiO2 distributed Bragg reflectors has been investigated from the viewpoint of the active-layer-thickness dependence of the interaction energy, the so-called vacuum Rabi splitting energy. The active layer thickness was changed from lambda/32 to lambda/5, where lambda corresponds to an effective resonant wavelength of the lowest-lying Z(3) exciton. We performed angle-resolved reflectance measurements, and clearly detected three cavity-polariton modes originating from the lower, middle, and upper polariton branches in a strong coupling regime of the Z(3) and Z(1,2) excitons, and cavity photon. The incidence-angle dependence of the cavity-polariton energies was analyzed with a phenomenological Hamiltonian for the strong coupling. The vacuum Rabi splitting energies are systematically controlled from 22 (37) to 68 (122) meV for the Z(3) (Z(1,2)) exciton with an increase in the active layer thickness. The active-layer-thickness dependence of the Rabi splitting energy is quantitatively explained using a simple model for quantum-well microcavities.

    DOI: 10.1016/j.phpro.2012.03.683

  • Cavity polaritons of heavy-hole and light-hole excitons in a CuI microcavity

    M. Nakayama, M. Kameda, T. Kawase, D. Kim

    PHYSICAL REVIEW B   83 ( 23 )   235325 (5 pages)   2011.06( ISSN:1098-0121

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    We have investigated the exciton-photon coupling phenomena in a CuI bulk microcavity consisting of a CuI active layer with an effective thickness of lambda/2 and HfO2/SiO2 distributed Bragg reflectors. In the CuI active layer, a thermal strain removes the degeneracy of the heavy-hole (HH) and light-hole (LH) excitons at the Gamma point. Angle-resolved reflectance spectra measured at 10 K demonstrate strong coupling between the HH and LH excitons and cavity photon, resulting in the formation of three cavity-polariton modes: lower, middle, and upper polariton branches. The photoluminescence band from the lower polariton branch was clearly observed. The energies of the three cavity-polariton modes as a function of incidence angle are reasonably explained by analysis using a phenomenological Hamiltonian for the strong coupling. The vacuum Rabi splitting energies are evaluated as 50 and 29 meV for the HH and LH excitons, respectively. The magnitude of the Rabi splitting energy results from the large oscillator strength of the relevant exciton. Furthermore, it is confirmed that the strong coupling regime is fully maintained at room temperature because of the high stability of the excitonic system.

    DOI: 10.1103/PhysRevB.83.235325

  • Control of exciton-photon interactions in CuCl microcavities

    M. Nakayama, K. Miyazaki, T. Kawase, D. Kim

    PHYSICAL REVIEW B   83 ( 7 )   075318 (5 pages)   2011.02( ISSN:1098-0121

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    We have investigated the active-layer-thickness dependence of exciton-photon interactions in planar CuCl microcavities with HfO(2)/SiO(2) distributed Bragg reflectors. The active layer thickness was changed from lambda/32 to lambda/4, while the cavity length was fixed at lambda/2. We performed angle-resolved reflectance measurements and clearly detected three cavity-polariton modes, originating from the lower, middle, and upper polariton branches, in a strong-coupling regime of the Z(3) and Z(1,2) excitons and cavity photon. The incidence-angle dependence of the cavity-polariton modes was analyzed using a phenomenological Hamiltonian for the strong coupling. It was found that the interaction energies of the cavity-polariton modes, the so-called vacuum Rabi splitting energies, are systematically controlled from 22(37) to 71(124) meV for the Z(3)(Z(1,2)) exciton by changing the active layer thickness from lambda/32 to lambda/4. The active-layer-thickness dependence of the Rabi splitting energy is quantitatively explained by a simple theory for quantum-well microcavities.

    DOI: 10.1103/PhysRevB.83.075318

  • Exciton polaritons in ZnO microcavities with different active layer thicknesses

    Toshiki Kawase, DaeGwi Kim, Kenichi Miyazaki, Masaaki Nakayama

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   248 ( 2 )   460 - 463   2011.02( ISSN:0370-1972

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    We have investigated the characteristics of exciton polaritons in ZnO microcavities with different active layer thicknesses. The microcavity was made from a bulk ZnO active layer and two distributed Bragg reflectors (DBRs) consisting of HfO2 and SiO2 layers. We adopted rf magnetron sputtering and pulsed laser deposition for the preparation of the DBR and ZnO active layer, respectively. Angle-resolved reflectance spectra demonstrate the formation of cavity polaritons. From the analysis using a phenomenological Hamiltonian for the coupling between the cavity photon and three kinds of excitons labeled A, B, and C peculiar to ZnO, the vacuum Rabi-splitting energies in the lambda/2-microcavity are estimated to be 30, 71, and 84 meV for the A, B, and C excitons, respectively. Moreover, we indicate the potential to control the Rabi-splitting energy by changing the active layer thickness. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI: 10.1002/pssb.201000620

  • Cavity polaritons of heavy-hole and light-hole excitons in a CuI microcavity

    M. Nakayama, M. Kameda, T. Kawase, and D. Kim

    Phys. Rev. B   83   235325 (5 pages)   2011

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  • Photoluminescence decay profiles of exciton-exciton scattering in a ZnO thin film

    S. Wakaiki, H. Ichida, K. Mizoguchi, D. Kim, Y. Kanematsu, and M. Nakayama

    Phys. Status Solidi C   8   116 - 119   2011

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  • Exciton polaritons in ZnO microcavities with different active layer thicknesses

    T. Kawase, D. Kim, K. Miyazaki, and M. Nakayama

    Phys. Status Solidi B   248   460 - 463   2011

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  • Control of exciton-photon interactions in CuCl microcavities

    M. Nakayama, K. Miyazaki, T. Kawase, and D. Kim

    Phys. Rev. B   83   075318 (5 pages)   2011

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  • 26aHA-8 Control of the Rabi-splitting energies in CuI microcavities

    Kameda M., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   66.1.4 ( 0 )   766   2011

  • 25pPSA-8 Contribution of 2s-exciton states to cavity polaritons in a ZnO microcavity

    Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   66.1.4 ( 0 )   747   2011

  • 25pPSA-50 Photoluminescence dynamics of energy transfer between CdS quantum dots

    Takahashi K., Shimura K., Okahara S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   66.1.4 ( 0 )   757   2011

  • 23pRB-2 Preparation of CuBr microcavitics and their optical properties

    Kanatani Y., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   66.2.4 ( 0 )   780   2011

  • 23aTN-1 Temperature dependence of energy transfer dynamics between colloidal quantum dots

    Takahashi K., Shimura K., Okahara S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   66.2.4 ( 0 )   777   2011

  • Photoluminescence decay profiles of exciton-exciton scattering in a ZnO thin film

    S. Wakaiki, H. Ichida, K. Mizoguchi, D. Kim, Y. Kanematsu, M. Nakayama

    Phys. Status Solidi C   8   116 - 119   2011

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  • Characteristics of exciton polaritons in a ZnO microcavity Reviewed

    Toshiki Kawase, Shingo Komura, Kenichi Miyazaki, DaeGwi Kim, Masaaki Nakayama

    PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES   42 ( 10 )   2567 - 2570   2010.09( ISSN:1386-9477

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    We have investigated the characteristics of exciton polaritons in a ZnO microcavity with HfO(2)/SiO(2) distributed Bragg reflectors. The results of the angle-resolved reflectance spectra were analyzed by calculating the cavity polariton dispersions with a phenomenological Hamiltonian for the coupling between the cavity photon and three kinds of excitons labeled A, B, and C peculiar to ZnO. The vacuum-Rabi-splitting energy is estimated to be similar to 80 meV. The reflectance dips originating from the cavity polaritons shift to lower energy side with an increase in temperature. We discuss the temperature dependence of the cavity-polariton energies of the ZnO microcavity on the basis of the phenomenological Hamiltonian taking account of the temperature dependence of the exciton energies with Varshni&apos;s law. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physe.2009.12.058

  • Characteristics of exciton polaritons in a ZnO microcavity Reviewed

    T. Kawase, S. Komura, K. Miyazaki, D. Kim, and M. Nakayama

    Physica E   42   2567 - 2570   2010

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  • Effects of distributed Bragg reflectors on temporal stability of CuCl microcavities Reviewed

    K. Miyazaki, D. Kim, T. Kawase, M. Kameda, and M. Nakayama

    Japanese Journal of Applied Physics   49   042802-1 - 042802-4   2010

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  • 21aHL-9 Active layer thickness dependence of cavity polaritons in ZnO microcavities

    Kawase T., Miyazaki K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   65.1.4 ( 0 )   753   2010

  • 25pPSB-10 Optical properties of a CuI microcavity with HfO_2/SiO_2 distributed Bragg reflectors

    Kameda M., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   65.2.4 ( 0 )   726   2010

  • 24aRG-3 Control of Rabi-splitting energy in ZnO microcavities

    Kawase T., Kim D., Nakayama N.

    Meeting Abstracts of the Physical Society of Japan   65.2.4 ( 0 )   695   2010

  • 23pRE-4 Photoluminescence dynamics of energy transfer between CdSe/ZnS quantum dots

    Yokota Y., Okazaki K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   65.2.4 ( 0 )   679   2010

  • Effects of distributed Bragg reflectors on temporal stability of CuCl microcavities Reviewed

    K. Miyazaki, D. Kim, T. Kawase, M. Kameda, M. Nakayama

    Japanese Journal of Applied Physics   49   042802-1 - 042802-4   2010

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  • Temperature dependence of the energy transfer of exciton states in bilayer structures of CdSe/ZnS quantum dots Reviewed

    DaeGwi Kim, Kanako Okazaki, Masaaki Nakayama

    PHYSICAL REVIEW B   80 ( 4 )   045322-1 - 045322-5   2009.07( ISSN:1098-0121

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    We have investigated the temperature dependence of an energy transfer (ET) between CdSe/ZnS quantum dots (QDs) measuring photoluminescence dynamics in a bilayer structure consisting of differently sized QDs. In the bilayer structure, an effective direct ET from donor QDs to acceptor QDs is realized. The temperature dependence of the observed ET rate can be classified into two categories. Under the condition that the thermal energy (k(B)T) is comparable to the splitting energy between the bright- and dark-exciton states and above, the observed ET rate is dominated by the thermal population behavior of the bright-exciton state: the ET rate increases with an increase in temperature. On the other hand, in the lower temperature region, the observed ET rate is almost constant, which may be due to a breakdown of the thermal equilibrium between the lower-lying dark-exciton state and the bright-exciton state.

    DOI: 10.1103/PhysRevB.80.045322

  • Layer-by-Layer Assembly of Colloidal CdS and ZnS-CdS Quantum Dots and improvement of Their Photoluminescence Properties Reviewed

    D. Kim, S. Okahara, K. Shimura, M. Nakayama

    JOURNAL OF PHYSICAL CHEMISTRY C   113 ( 17 )   7015 - 7018   2009.04( ISSN:1932-7447

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    Thin films of colloidal US and ZnS-CdS alloy quantum dots (QDs) were fabricated by layer-by-layer (LBL) self-assembly to synthesize blue luminescent QD thin films. The assembly of negatively charged colloidal QDs and positively charged poly(diallyldimethylammonium chloride) results in QD/polymer multilayers. The relative intensity of the band-edge photoluminescence (PL) to that of the defect-related PL was decreased during the LBL assembly process. With an additional dipping treatment in a Cd(ClO(4))(2) aqueous solution with pH 10, the band-edge PL intensity was recovered. The PL decay profiles before and after the dipping treatment were considerably different. From this fact, we conclude that the enhancement of the band-edge PL intensity originates from the reduction of nonradiative recombination processes at the QD surface.

    DOI: 10.1021/jp810577p

  • Experimental determination of the excitonic dispersion relation from the center-of-mass quantization effect on excitons in PbI2 thin films Reviewed

    G. Oohata, Y. Yokotsuji, D. Kim, H. Ishihara, and M. Nakayama

    Journal of Physical Society of Japan   78   024702-1 - 024702-5   2009

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  • Temperature dependence of the energy transfer of exciton states in bilayer structures of CdSe/ZnS quantum dots Reviewed

    D. Kim, K. Okazaki, and M. Nakayama

    Physical Review B   80   045322-1 - 045322-5   2009

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  • Layer-by-layer assembly of colloidal CdS and ZnS-CdS quantum dots and improvement of their photoluminescence properties Reviewed

    D. Kim, S. Okahara, K. Shimura, and M. Nakayama

    Journal of Physical Chemistry C   113   7015 - 7018   2009

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  • Exciton polaritons in bulk CuCl microcavities grown by vacuum deposition Reviewed

    G. Oohata, T. Nishioka, D. Kim, H. Ishihara, and M. Nakayama

    Physica Status Solidi C   6   280 - 283   2009

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  • 25aXB-2 Temperature dependence of energy transfer between CdS quantum dots

    Shimura K., Okahara S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   64.2.4 ( 0 )   611   2009

  • 30aVD-2 Photoluminescence dynamics of energy transfer between colloidal CdS quantum dots III

    Kim D., Okahara S., Shimura K., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   64.1.4 ( 0 )   764   2009

  • 28pPSA-10 Preparation of CuCl microcavities with distributed Bragg reflector consisting of HfO_2 and SiO_2 multiple layers II

    Miyazaki K., Oohata G., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   64.1.4 ( 0 )   738   2009

  • 28aXB-9 Temperature dependence of cavity polariton dispersion in a ZnO microcavity

    Kawase T., Miyazaki K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   64.2.4 ( 0 )   684   2009

  • 28aXB-8 Control of Rabi-splitting in CuCl microcavities with HfO_2/SiO_2 distributed Bragg reflector

    Miyazaki K., Kawase T., Oohata G., Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   64.2.4 ( 0 )   684   2009

  • Exciton polaritons in bulk CuCl microcavities grown by vacuum deposition Reviewed

    G. Oohata, T. Nishioka, D. Kim, H. Ishihara, M. Nakayama

    Physica Status Solidi C   6   280 - 283   2009

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  • Experimental determination of the excitonic dispersion relation from the center-of-mass quantization effect on excitons in PbI2 thin films Reviewed

    G. Oohata, Y. Yokotsuji, D. Kim, H. Ishihara, M. Nakayama

    Journal of Physical Society of Japan   78   024702-1 - 024702-5   2009

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  • Experimental Determination of Excitonic Dispersion Relation from Center-of-Mass Quantization Effect on Excitons in PbI<SUB>2</SUB> Thin Films

    Oohata Goro, Yokotsuji Yuta, Kim DaeGwi, Ishihara Hajime, Nakayama Masaaki

    Journal of the Physical Society of Japan   78 ( 2 )   024702 - 024702   2009( ISSN:00319015

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    We have investigated the center-of-mass quantization effect on excitons in layered-compound PbI<SUB>2</SUB> ultra-thin films by precisely changing the layer thickness from 7 to 20 monolayers. Crystalline PbI<SUB>2</SUB> thin films that are fully oriented along the <I>c</I>-axis were prepared by a vacuum deposition method. We confirmed that the surface roughness of the prepared thin films corresponds to one monolayer owing to the van der Waals interaction along the <I>c</I>-axis peculiar to the layered compound, which is advantageous for the realization of the center-of-mass quantization effect. The optical spectra, such as absorption, transmittance, and reflectance clearly exhibit oscillatory structures originating from the quantized excitonic states with a quantum number of up to 15: the quantization energy amounts to ∼130 meV. From the analysis of the systematic results of the center-of-mass quantization, we experimentally determined the excitonic dispersion relation of PbI<SUB>2</SUB>, which is well explained by a tight-binding exciton model instead of a usually used effective-mass model.

    DOI: 10.1143/jpsj.78.024702

    CiNii Article

  • Experimental verification of Forster energy transfer between semiconductor quantum dots Reviewed

    D. Kim, S. Okahara, Y. Shim, M. Nakayama

    Physical Review B   78   153301-1 - 153301-4   2008.10

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  • Temperature dependence of photoluminescence dynamics in colloidal CdS quantum dots Reviewed

    D. Kim, T. Mishima, K. Tomihira, M. Nakayama

    Journal of Physical Chemistry C   112   10668 - 10673   2008.06

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  • Highly efficient preparation of size-controlled CdS quantum dots with high photoluminescence yield Reviewed

    D. Kim, K. Tomihira, S. Okahara, M. Nakayama

    Journal of Crystal Growth   310   4244 - 4247   2008.06

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  • 23pYJ-2 Control of Rabi-splitting in CuCI microcavities with distributed Bragg reflector

    Oohata G., Nishioka T., Miyazaki K., Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.1.4 ( 0 )   704   2008

  • 23pYJ-1 Optical properties of ZnO microcavities with distributed Bragg reflector

    Komura S., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.1.4 ( 0 )   704   2008

  • 23aYJ-2 Photoluminescence dynamics of energy transfer between colloidal CdS quantum dots II

    Okahara S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.1.4 ( 0 )   694   2008

  • 23aYH-6 Active-layer thickness dependence of Rabi-splitting in CuCl microcavities

    Oohata G., Okugawa Y., Miyazaki K., Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.2.4 ( 0 )   688   2008

  • 23aYH-5 Preparation of CuCl microcavities with distributed Bragg reflector consisting of HfO_2 and SiO_2 multiple layers

    Miyazaki K., Oohata G., Kawase T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.2.4 ( 0 )   687   2008

  • 22aPS-24 Optical properties of ZnO microcavities with distributed Bragg reflector II

    Kawase T., Komura S., Miyazaki K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.2.4 ( 0 )   655   2008

  • 21aYH-1 Phtoluminescence dynamics in colloidal CdS quantum dots

    Kim D., Tomihira K., Okahara S., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   63.2.4 ( 0 )   640   2008

  • Observation of Exciton Polaritons in a ZnO Microcavity with HfO<SUB>2</SUB>/SiO<SUB>2</SUB> Distributed Bragg Reflectors

    Nakayama Masaaki, Komura Shingo, Kawase Toshiki, Kim DaeGwi

    Journal of the Physical Society of Japan   77 ( 9 )   093705 - 093705   2008( ISSN:00319015

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    We have investigated the characteristics of the exciton polaritons in a ZnO microcavity. The microcavity consists of an effective one-wavelength thick ZnO active layer and HfO<SUB>2</SUB>/SiO<SUB>2</SUB> distributed Bragg reflectors (DBRs) at the bottom and top. We adopted rf magnetron sputtering and pulsed laser deposition for the preparation of the DBR and ZnO layer, respectively. Angle-resolved reflectance and photoluminescence spectra demonstrate the formation of the cavity polaritons. The cavity polariton dispersions are analyzed using a phenomenological Hamiltonian for the coupling between the cavity photon and three kinds of fundamental excitons labeled A, B, and C. The vacuum Rabi splitting energy is estimated to be ∼80 meV. The giant Rabi splitting energy reflects the large exciton oscillator strength of ZnO.

    DOI: 10.1143/jpsj.77.093705

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  • Energy-relaxation dynamics of photogenerated excitons observed from time-resolved photoluminescence of exciton-exciton scattering in CuI thin films Reviewed

    Hideki Ichida, Yasuo Kanematsu, Kohji Mizoguchi, DaeGwi Kim, Masaaki Nakayama

    PHYSICAL REVIEW B   76 ( 8 )   085417/01 - 05   2007.08( ISSN:1098-0121

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  • Self-assembled formation of ZnO hexagonal micropyramids with high luminescence efficiency Reviewed

    DaeGwi Kim, Shuji Wakaiki, Shingo Komura, Masaaki Nakayama, Yukimasa Mori, Kazuyo Suzuki

    APPLIED PHYSICS LETTERS   90 ( 10 )   2007.03( ISSN:0003-6951

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    The authors have found the self-assembled formation of ZnO hexagonal micropyramids after the growth of a sufficiently thick ZnO layer on a (0001) Al2O3 substrate by rf-magnetron sputtering deposition. It was confirmed by scanning electron microscopy that the orientations of the micropyramids are well arranged. The reflection and photoluminescence spectra at 10 K demonstrate that optical properties of the total growth layer are of high quality. The noticeable discovery with the use of cathodoluminescence spectroscopy is that the luminescence intensity of the micropyramids is 30 times stronger than that of the underlying layer; namely, strong enhancement of luminescence is realized in the self-assembled micropyramids. (c) 2007 American Institute of Physics.

    DOI: 10.1063/1.2713123

  • 21aTQ-3 Giant Rabi-splitting in CuCl microcavities with distributed Bragg reflector

    Nishioka T., Oohata G., Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   62.2.4 ( 0 )   721   2007

  • 21aTQ-2 Thickness dependence on the center-of-mass quantization of exciton in PbI_2 nano-films : Determination of the excitonic dispersion relation.

    Yokotsuji Y., Oohata G., Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   62.2.4 ( 0 )   721   2007

  • 20pZC-2 Observation of biexciton-resonant hyper-parametric scattering in SiO_2/CuCI layered structures

    Nishioka T., Wakaiki S., Oohata G., Kim D., Mizoguchi K., Edamatsu K., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   62.1.4 ( 0 )   751   2007

  • 19pPSA-48 Photoluminescence dynamics of ZnS-CdS alloy quantum dots prepared by a colloidal method

    Okahara S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   62.1.4 ( 0 )   728   2007

  • 19aZB-1 Optical properties of ZnO hexagonal micropyramids prepared by an rf-magnetron sputtering method

    Komura S., Wakaiki S., Kim D., Mizoguchi K., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   62.1.4 ( 0 )   709   2007

  • Photoluminescence properties and energy transfer processes from excitons to Mn2+ ions in Mn2+-doped CdS quantum dots prepared by a reverse-micelle method Reviewed

    D. Kim, M. Miyamoto, M. Nakayama

    JOURNAL OF APPLIED PHYSICS   100 ( 9 )   2006.11( ISSN:0021-8979

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    We investigated the photoluminescence (PL) properties of Mn2+-doped CdS (CdS:Mn2+) quantum dots (QDs) prepared by a reverse-micelle method. A PL band which originates from the intracation transition, the so-called d-d transition, of tetrahedrally coordinated Mn2+ ions, is clearly observed at similar to 2.1 eV, indicating that Mn2+ ions are thoroughly doped inside CdS QDs. By surface modification with a Cd(OH)(2) layer, the intensity of the Mn2+-related PL band is increased approximately ten times compared with that without modification, and strong enhancement of the band-edge PL band is observed. The decay profile of the band-edge PL in surface-modified CdS:Mn2+ QDs is much faster than that in undoped CdS QDs; this shortened decay time originates from the effective energy transfer process from the excitons of host QDs to Mn2+ ions. The PL decay profiles are quantitatively explained on the basis of a three-level model including both the dark-exciton state and the energy transfer process. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2363238

  • Center-of-mass quantization of excitons in PbI2 thin films grown by vacuum deposition Reviewed

    M. Nakayama, D. Kim, H. Ishihara

    PHYSICAL REVIEW B   74 ( 7 )   2006.08( ISSN:1098-0121

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    We have investigated excitonic properties of PbI2 thin films grown on a (001) NaCl substrate by a conventional vacuum deposition technique. The x-ray-diffraction patterns indicate that the crystal structure of the PbI2 thin films is just oriented along the [001] crystal axis. The surface morphology observed by an atomic force microscope shows that the surface roughness is within 1 nm. These results of the structural analysis demonstrate that the PbI2 thin films are suitable for the investigation of quantization effects. The absorption spectra of 8-, 10-, and 15-nm-thick films clearly exhibit oscillatory structures in the energy region higher than the fundamental exciton transition up to similar to 110 meV. This fact indicates the nice realization of the center-of-mass quantization of the exciton; however, the usually used model that is the wave-vector quantization of a parabolic exciton band could not be reasonably applied to explain the quantized exciton energies. The absorption spectra are quantitatively analyzed on the basis of a tight-binding exciton model for the energy dispersion using a nonlocal theory of linear optical response.

    DOI: 10.1103/PhysRevB.74.073306

  • 28aPS-58 Photoluminescence dynamics of energy transfer between CdS quantum dots prepared by a colloidal method II

    Tomihira K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   61.1.4 ( 0 )   738   2006

  • 28aPS-21 Optical response of excitons in homo-epitaxial ZnO thin films grown by an rf-magnetron sputtering method

    Wakaiki S., Komura S., Kim D., Mizoguchi K., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   61.1.4 ( 0 )   729   2006

  • 25aPS-25 Center-of-mass quantization of excitons in PbI_2 thin films grown by vacuum deposition

    Kim D., Ishihara H., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   61.2.4 ( 0 )   602   2006

  • 24aRA-2 Optical properties of CdSe quantum dots prepared by a single source precursor method

    Kuwabara T., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   61.2.4 ( 0 )   580   2006

  • Strong enhancement of band-edge photoluminescence in CdS quantum dots prepared by a reverse-micelle method Reviewed

    D Kim, M Miyamoto, T Mishima, M Nakayama

    JOURNAL OF APPLIED PHYSICS   98 ( 8 )   2005.10( ISSN:0021-8979

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    We have investigated the effects of surface modification on photoluminescence (PL) properties of CdS quantum dots (QDs) prepared by a reverse-micelle method. It is demonstrated that the modification of QD surface with a Cd(OH)(2) layer leads to a strong enhancement of the band-edge PL intensity of CdS QDs in reverse micelles. The PL-decay profile before the surface modification exhibits a fast decay component less than 50 ps. After the modification, the fast-decay component disappears. The drastic change of the PL-decay profiles before and after the surface modification corresponds to the marked increase of the PL intensity. This suggests that the strong enhancement of the band-edge PL intensity originates from the remarkable reduction of nonradiative recombination processes, which usually result in a very short decay time, due to surface defects of QDs.

    DOI: 10.1063/1.2106008

  • Photoluminescence dynamics of exciton-exciton scattering processes in CuI thin films Reviewed

    Hideki Ichida, Yasuo Kanematsu, Takeya Shimomura, Kohji Mizoguchi, DaeGwi Kim, Masaaki Nakayama

    PHYSICAL REVIEW B   72 ( 4 )   045210/01 - 05   2005.07( ISSN:1098-0121

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  • Optical properties of high-quality ZnO thin films grown by a sputtering method Reviewed

    T Shimomura, D Kim, M Nakayama

    JOURNAL OF LUMINESCENCE   112 ( 1-4 )   191 - 195   2005.04( ISSN:0022-2313

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    We have investigated optical properties of high-quality ZnO thin films grown by a sputtering method. By introducing a low-temperature buffer layer of ZnO, the lattice-misinatched strain is relaxed and the crystallinity is improved remarkably. In the absorption spectrum at 10 K, the absorption peaks of the A and B excitons are observed. In the photo luminescence (PL) spectrum, the free-exciton PL is observed and the defect-related PL is negligibly weak. These results clearly indicate high crystallinity of the film. Furthermore, under high-density excitation conditions, a PL band originating from an inelastic scattering process of excitons, the so-called P emission, is observed in the ZnO thin film. (c) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jlumin.2004.09.054

  • Optical properties of ZnS-CdS alloy quantum dots prepared by a colloidal method Reviewed

    K Tomihira, D Kim, M Nakayama

    JOURNAL OF LUMINESCENCE   112 ( 1-4 )   131 - 135   2005.04( ISSN:0022-2313

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    We have investigated optical properties of ZnS-CdS alloy (Zn1-xCdxS) quantum dots (QDs) prepared by a colloidal method. We succeeded in the preparation of Zn1-xCdxS QDs for all alloy compositions of x between 0 and 1. Furthermore, the reduction of the size-distribution width was achieved by using a size-selective photoetching treatment. The intensity of the band-edge luminescence was remarkably increased by modifying the surface with a Cd(OH)(2) layer. The surface modification also causes drastic changes of decay profiles of the band-edge luminescence, reflecting considerable suppression of nonradiative decay processes. These results clearly demonstrate the success in the preparation of the size- and surface-controlled Zn1-xCdxS QDs. (c) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jlumin.2004.09.011

  • 24aPS-81Photoluminescence properties of ZnO thin films prepared by a sputtering method under high excitation power conditions

    Shimomura T., Kim D., Mizoguchi K., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   60.1.4 ( 0 )   677   2005

  • 21aXF-2 Photoluminescence dynamics of energy transfer between CdS quantum dots prepared by a colloidal method

    Tomihira K., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   60.2.4 ( 0 )   605   2005

  • 20pPSA-16 Photoluminescence properties of ZnO thin films grown by chloride vapor phase epitaxy

    Wakaiki S., Kim D., Nakayama M.

    Meeting Abstracts of the Physical Society of Japan   60.2.4 ( 0 )   585   2005

  • Quantum-Disk Excitons and Their Interaction with Phonons in BiI3

    Kim DaeGwi, Karasawa Tsutomu, Iida Takeshi, Komatsu Teruo

    Journal of the Physical Society of Japan   74 ( 4 )   1309 - 1319   2005( ISSN:00319015

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    We investigate excitonic transitions and exciton–phonon interactions in disk-shaped microcrystallites of layered BiI<SUB>3</SUB> in CdI<SUB>2</SUB> matrices. We have observed the optical spectra and analyze the results theoretically introducing a quantum disk model of the disk-shaped microcrystallites. The absorption band of the excitons confined in the microcrystallite has been observed in the energy region higher than the bulk exciton transition energy. For the resonant excitations within the absorption band, luminescence bands have been observed with Stokes shifts whose magnitudes are different depending on the excitation energies; the Stokes shift decreases with increasing the excitation energy. This is the first observation of the luminescence from the relaxed state of exciton, that is, the self-trapped exciton (STE) state in the microcrystallite. We show that the observed absorption and luminescence spectra can be reproduced by the model calculations with taking into account the disk-size dependent exciton–phonon interaction and the disk-size distribution observed in our previous work. From the temporal behavior of the luminescence, we find that the decay-time constant becomes shorter with the decrease in the detecting energy, while it becomes longer with decreasing temperature especially below 4.2 K. It is shown that such anomalous behavior of the size and temperature dependence of the decay time constant are well described in terms of the spin-multiplet splitting of the STE states and the size-dependent acoustic phonon interaction.

    DOI: 10.1143/jpsj.74.1309

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Outline of collaborative research (seeds)

  • 半導体超微粒子・超薄膜の作製と光物性

    随時

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    Request for collaborative research:The private sector, such as other institutions

    Type of research exchange:Technical consultation, Contract research, Joint research

    Application fields / methods etc:新しい光学材料としての可能性。

    半導体超微粒子・超薄膜は強い光学的非線形性と超高速応答を示すことから新しいオプトエレクトロニクス材料として期待がかけられている。これら試料作製とサイズの制御、光学特性のサイズ依存性について研究を行う。

Grant-in-Aid for Scientific Research

  • 半導体量子ドットナノ秩序構造体の創成と新規光機能の解明

    Grant-in-Aid for Scientific Research(B)  2020.04

  • 近接した半導体ナノ粒子間の相互作用メカニズムの解明と新規光機能性

    Grant-in-Aid for Scientific Research(C)  2012.04

  • 半導体ナノ粒子間のエネルギー移動過程の制御と新規光機能性

    Grant-in-Aid for Scientific Research(C)  2008.04

  • 半導体量子ドット間のエネルギー移動過程の解明と制御

    Grant-in-Aid for Young Scientists(B)  2005.04

Other subsidies, etc.

  • 太陽電池への応用に向けたCIS系半導体ナノ粒子の作製と積層構造の制御

    未設定  2009.04

  • 半導体ナノ粒子の発光メカニズムの解明と高効率発光材料の開発

    未設定  2007.04

Charge of on-campus class subject

  • <学>物理光学

    2017     Undergraduate

  • <学>電磁気学II

    2017     Undergraduate

  • <院>ナノマテリアル工学特論

    2017     Graduate school

Visiting Lectures ⇒ Link to the list of Visiting Lectures

  • 無限の可能性を秘めたナノ粒子

    Category:Modern system science (knowledge information system, environmental system, educational welfare, psychology), Commerce (management, public management), Economics, Law (law, politics, administration), Literature (literature, philosophy, history, art, human behavior, language, culture, society / gender), Science (mathematics, physics, chemistry, biology, geology, biochemistry), Engineering (machinery, electronics / physics, electrical / electronics, electrical information, chemical biotechnology, architecture, cities (civil engineering / environment), material chemistry, aerospace, marine systems, applied chemistry, chemistry, materials), Life sciences (food, nutrition science, living environment, human welfare), Agricultural science (applied biology, biofunctional chemistry, green space environmental science), Medicine (medical care, rehabilitation, health exercise science, physical fitness / training, sports practice science), Nursing (nursing, sex education), Veterinary

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    Audience:General

    ナノ粒子の面白さ、ナノ粒子の作り方、ナノ粒子の物性、将来の可能性などに関する講演
    ナノ粒子のもつ可能性について解説する

Job title

  • Job title within the department

    Graduate School of Engineering Division of Physics and Electronics 

    専攻長  2024.04

  • Job title within the department

    School of Engineering 

    副学部長  2022.04 - 2024.03

Other

  • Job Career

    2012.10 - Now

  • Job Career

    2007.04 - 2012.09

  • Job Career

    2002.10 - 2007.03

  • Job Career

    1997.04 - 2002.09