Spectroscopy of Non-Radiative Recombination Centers in Blue-Light Emitting Semiconductors by Two-Wavelength Excitation Scheme

通过双波长激发方案对蓝光发射半导体中的非辐射复合中心进行光谱分析

• 批准号: 12650003
• 负责人: KAMATA Norihiko
• 金额: $ 1.54万
• 依托单位: Saitama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650003/
• 关键词: photoluminescence; non-radiative recombination center; internal quantum efficiency; two-wavelength excited phptoluminescence; blue-light emitting semiconductor; GaN; below-gap state; galium nitride

1. Analog Measurement System and Excitation Density Dependence :In addition to single-photon-counting, we arranged an analog measurement system by introducing a low-noize lock-in amplifier. The dependence of an above-gap excitation (AGE) density on the PL intensity decrease due to a below-gap excitation (BGE) light was measured for a GaN grown by MOCVD. The result agreed well with our two-states model.A filtered D_2 lamp (4.1 eV) and aNd : YAG laser (1.17 eV) were used as an AGE and BGE light sources.2. Temperature Dependence of the BGE effect:The normalized PL intensity defined as the ratio of PL intensities with and without BGE, I_<A+B>/I_A, was unity above 150 K in case of a donor-acceptor pair (DAP) luminescence of a GaN epitaxial layer. With lowering the temperature below 150K, it decreased steeply down to 0.42 and then became constant below 80K. This is attributed to a thermal emission of electrons from the upper level of the two-states model to the conduction band. A thermal activation energy of 0.1 eV *s calculated by curve fitting, which was consistent with our previous energy determination of the level. No distinct temperature dependence of yellow luminescence is important to analyze nonradiative recombination (NRR) processes.3. Below-Gap States in GaN-based Semiconductors:Based on these results on GaN, InGaN/GaN and GaN/AlGaN multiple quantum well structures, we summarized the spatial and energy distribution, density and capture coefficients of NRR centers detected by our two-wavelength excited PL. They were presented at International Conferences and published in Academic Journals on the list.

1.模拟测量系统和激发密度依赖性：除了单光子计数外，我们还通过引入低噪声锁定放大器来安排模拟测量系统。测量了MOCVD生长GaN的能隙上激发（AGE）密度对由于能隙下激发（BGE）光导致的PL强度降低的依赖性。实验结果与我们提出的双态模型吻合较好.实验中使用了4.1eV的D_2灯和1.17eV的Nd：YAG激光作为AGE和BGE的光源. BGE效应的温度依赖性：在GaN外延层的施主-受主对（DAP）发光的情况下，归一化的PL强度定义为有和没有BGE的PL强度之比I_<A+B>/I_A，在150 K以上为1。当温度低于150 K时，它急剧下降到0.42，然后在80 K以下趋于稳定。这归因于电子从两态模型的上能级到导带的热发射。通过曲线拟合计算的热激活能为0.1 eV *s，这与我们先前对能级的能量测定一致。黄光发光的温度依赖性不明显，这对分析非辐射复合（NRR）过程是很重要的. GaN基半导体中的带隙下态：基于GaN、InGaN/GaN和GaN/AlGaN多量子阱结构的实验结果，总结了我们的双波长激发光致发光探测到的NRR中心的空间分布、能量分布、密度和俘获系数。他们在国际会议上提出，并发表在学术期刊上的名单。

项目成果

N.Kamata, J.M.Z.Ocampo, T.Someya, K.Arakawa et al.: "Suppression of yellow luminescence in multiple quantum wells revealed by below-gap excitation spectroscopy"Proc.Int.Conf.on Physics of Semiconductors,Springer Proc.in Physics. 87. 1521-1522 (2001)

N.Kamata、J.M.Z.Ocampo、T.Someya、K.Arakawa 等人：“带隙激发光谱揭示的多量子阱中黄色发光的抑制”Proc.Int.Conf.on 半导体物理学，Springer Proc.in

J. M. Z. Ocampo, N. Kamata, T. Someya, Y. Arakawa et al.: "Extremely slow relaxation processes of a yellow-luminescence-relared state in GaN revealed by two-wavelength excited photoluminescence"Phys. Stat. Sol. (b). 228. 433-436 (2001)

J. M. Z. Ocampo、N. Kamata、T. Someya、Y. Arakawa 等人：“双波长激发光致发光揭示了 GaN 中黄色发光相关态的极其缓慢的弛豫过程”。

N.Kainata, J.M.Z.Ocamnpo, T.Someya, Y.Arakawa et al.: "Below-gap recombination dynamics in GaN revealed by time-resolved and two-wavelength excited photolumninescence"Materials Science and Engineering B. (to be published).

N.Kainata、J.M.Z.Ocamnpo、T.Someya、Y.Arakawa 等人：“时间分辨和双波长激发光致发光揭示的 GaN 中的带隙下方复合动力学”材料科学与工程 B.（待出版）。

N.Kamata, J.M.Z.Ocampo, T.Someya, K.Arakawa et al.: "Temperature dependence of photoluminescence intensity change due to below-gap excitation in GaN"Inst.of Phys.Conf.Series. (to be published).

N.Kamata、J.M.Z.Ocampo、T.Someya、K.Arakawa 等人：“GaN 中带隙以下激发导致的光致发光强度变化的温度依赖性”Inst.of Phys.Conf.Series。

N.Kamata, J.M.Z.Ocamnpo, T.Someya, Y.Arakawa et al.: "Temperature dependence of photoluminescence intensity change due to below-gap excitation in GaN"Inst. of Phys. Conf. Series. (to be published).

N.Kamata、J.M.Z.Ocamnpo、T.Someya、Y.Arakawa 等人：“GaN 中带隙以下激发导致的光致发光强度变化的温度依赖性”Inst.