Quantum capture dynamics between different semiconductor quantum structures

不同半导体量子结构之间的量子捕获动力学

基本信息

批准号：
11650020
负责人：
FUJIWARA Kenzo
金额：
$ 2.11万
依托单位：
KYUSHU INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In order to pursue mechanisms behind the competitive quantum capture processes of photogenerated carriers as a function of lattice temperature in electronically isolated semiconductor quantum wells with different well thicknesses, photoluminescence (PL) emission dynamics have been investigated and following results are obtained.1. Existence of quantum capture processes in PL emission spectraPicosecond time-resolved PL experiments have been undertaken in quantum well samples consisting of three or four different size wells. It is experimentally found that the lower energy emission bands show much weaker PL intensities than the higher energy ones, as opposed to the PL intensity distribution expected in thermal equilibrium conditions. The unique PL characteristics observed in several samples reflect the quantum capture processes and the dynamics exhibit, for example, much shorter PL lifetimes than the radiative recombination lifetimes.2. Temperature effects on quantum capture dynamicsIt i … More s experimentally demonstrated that the PL recombination dynamics originating from the observed competitive capture of photoexcited carriers between the quantum wells exhibit totally different temperature effects from the ones already known for the radiative recombination lifetimes of two dimensional excitons.3. Dependence of well width fluctuations on quantum capture dynamicsQuantum capture dynamics have been studied in composite GaAs quantum wells with monolayer growth island terraces, prepared by growth-interrupted molecular beam epitaxy. From detailed analysis of the PL results, it is newly discovered that the PL intensity distribution as well as the dynamics are both significantly influenced by relative energy positions of the first excited subband state to the barrier band edge. In addition, the transfer proceeses of excitons are confirmed between the island terraces.4. Mechanisms of quantum capture dynamics in composite quantum well systemsFrom comparison between two similar composite quantum well samples but with different configurations of outer clad layers (AlGaAs alloy and GaAs/AlAs superlattice digital alloy), it is found that both the PL intensity distribution and the dynamics including the temperature dependence are very different each other. These results suggest that mechanisms behind the quantum capture processes are sensitive to the subband energy structures of the clad layers, from which photogenerated carriers are distributed to the different wells with different subband energy structures. Less

为了探究不同阱厚度的电子隔离半导体量子阱中光生载流子竞争量子捕获过程随晶格温度变化的机制，对光致发光（PL）发射动力学进行了研究，并获得了以下结果。 1． PL发射光谱中的量子捕获过程已经在由三个或四个不同尺寸的阱组成的量子阱样品中进行了皮秒时间分辨PL实验，实验发现较低能量的发射带显示出更弱的能量。 PL 强度高于高能量的 PL 强度，与热平衡条件下预期的 PL 强度分布相反，在几个样品中观察到的独特 PL 特性反映了量子捕获过程和动力学，例如，PL 寿命比辐射复合短得多。 2. 温度对量子捕获动力学的影响实验证明，源自观察到的量子阱之间光激发载流子的竞争捕获的 PL 复合动力学表现出与量子阱之间完全不同的温度效应。二维激子的辐射复合寿命已为人所知。 3. 阱宽度波动对量子捕获动力学的依赖性已经在具有单层生长岛阶的复合 GaAs 量子阱中研究了量子捕获动力学，该复合 GaAs 量子阱是通过生长中断分子束外延制备的。通过对 PL 结果的分析，新发现 PL 强度分布以及动力学都受到第一激发子带态相对于势垒带边缘的相对能量位置的显着影响。岛台之间的激子转移过程得到证实。 4．复合量子阱系统中量子俘获动力学机制通过比较两种相似但外包层结构不同的复合量子阱样品（AlGaAs合金和GaAs/AlAs超晶格数字合金）。），发现 PL 强度分布和包括温度依赖性在内的动力学彼此非常不同。这些结果表明量子捕获过程背后的机制对包层的子带能量结构敏感。层，光生载流子从这些层分布到具有不同子带能量结构的不同阱。