Grant-in-Aid for Scientific Research (C).
Applied optics/Quantum optical engineering
|Research Institution||Saitama University|
KAMATA Norihiko Faculty of Engineering, Saitama University Assoc. Prof., 工学部, 助教授 (50211173)
|Project Fiscal Year
1998 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥1,100,000 (Direct Cost : ¥1,100,000)
|Keywords||non-radiative recombination center / below-gap state / photoluminescence / quantum well / band-to-band emission / internal quantum efficiency / light emitting devices / non-radiative recombination parameters / 非発光再結合準位 / 禁制帯内準位 / フォトルミネッセンス / 量子井戸構造 / バンド間発光 / 内部量子効率 / 半導体発光デバイス / 非発光最結合パラメーター / 非発光再結合パラメーター / 2波長励起フォトルミネッセンス / 非発光再結合パラメータ|
1. General : By observing the intensity change of band-to-band photoluminescence (PL) due to the superposition of a below-gap excitation (BGE) light on an above-gap excitation (AGE) light, a quantitative study on nonradiative recombination (NRR) centers in bulk and multiple quantum well (MQW) semiconductors became possible. Lowering the AGE density down to the single-photon-counting level improved the sensitivity of finding NRR centers. The energy distribution of the NRR centers and their spatial distribution in MQW structures became clear by tuning the energy of AGE and BGE.
2. Results in GaAs/AlGaAs MQW :
(1) Various levels were detected in undoped and Si-doped samples, reflecting their structures and growth conditions.
(2) Spatial and energy distribution of traps was determined by considering AGE and BGE energy dependence.
(3) Contrary to uniform-doping, absence of NRR centers in modulation-doped well layers became clear for the first time.
(4) Trap parameters were determined self-consistently by considering the AGE and BGE density dependence.
3. Results in GaN-based Semiconductors :
(1) In InGaN/GaN MQW, NRR centers were found in GaN layers with the BGE energy region between 1.6 and 2.4 eV.
(2) The same energy distribution was obtained in bulk GaN sample, indicating the consistency with the result of MQW.
(3) NRR centers in GaN/AlGaN MQW were detected, which can be utilized for analyzing detailed recombination dynamics.