GaNAs/GaAs量子阱的激子局域化以及退局域化(英文)  

Exciton Localization and Delocalization in GaNAs/GaAs Quantum Wells

作　　者：罗向东[1] 徐仲英[1] 葛惟琨[2] 

机构地区：[1]中国科学院半导体研究所超晶格国家重点实验室,北京100083 [2]香港科技大学物理系

出　　处：《发光学报》2002年第2期109-113,共5页Chinese Journal of Luminescence

基　　金：国家自然科学基金资助项目 ( 199740 45 );中国科学院纳米科学技术项目基金资助项目~~

摘　　要：我们利用光荧光 (PL)以及时间分辨光谱 (TRPL)研究了用MBE生长在GaAs衬底上的GaNAs/GaAs量子阱的激子局域化以及退局域化。研究发现 ,在低温下用连续光 (CW)激发 ,由于GaNAs中势振荡所产生的局域激子发光是所测量到光谱的主要发光来源。然而在脉冲激发下 ,情况完全不同。在高载流子密度激发或者高温下GaNAs/GaAs量子阱中例外 ,一个高能端的PL峰成为了主要的发光来源。通过研究 ,我们将这个新的发光峰指认为量子阱中非局域激子复合的PL峰。这个发光峰在温度和激发强度的变化过程中与局域激子相互竞争。我们相信这一过程也是许多文献所报道的在InGaN和AlGaN等氮化物中经常观测到的发光峰位随温度“S”We have studied exciton localization and delocalization effect in GaNAs/GaAs quantum wells (QWs) grown by molecular beam epitaxy (MBE) using photoluminescence (PL) and time-resolved PL measurements. Studied results suggest that, at low temperature and under a conventional CW excitation, measured PL spectra were dominated by localized exciton (LE) emission caused by potential fluctuations in GaNAs layer. However, under short pulse laser excitation, it is different. An extra high-energy PL peak comes out from GaNAs/GaAs QWs and dominates the PL spectra under high excitation and/or at high temperature. By investigation, we have attributed the new PL peak to the recombination of delocalized excitons in QWs. This recombination process competes with the localized exciton emission, which, we believe, constitutes the 'S-shaped' temperature-dependent emission shift often reported in ternary nitrides of InGaN and AlGaN in the literature.

关 键 词：激子局域化 退局域化 GaNAs 量子阱 GAAS 砷化镓 半导体材料 光谱学 镓砷氮化合物 

分 类 号：O472.3[理学—半导体物理] TN304.26[理学—物理]