A Study of Two-Dimensional Exciton Localization and Mobility Edge by Ultrafast Time-Resolved Spectroscopy

超快时间分辨光谱研究二维激子局域化和迁移边缘

• 批准号: 61540221
• 负责人: NAKAMURA Arao
• 金额: $ 1.15万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540221/
• 关键词: short-period superlattices; picosecond time-resolved spectroscopy; exciton localization; two-dimensional excitons; carrier sink; Tunneling effect; 共鳴トンネル効果; トンネル効果を伴った再結合過程; 二次元励起子量子井戸のキャリヤ吸い込み; short-period superlattices; picosecond time-resolved spectroscopy; exciton localization; two-dimensional excitons; carrier sink; Tunneling effect; 共鳴トンネル効果; トンネル効果を伴った再結合過程; 二次元励起子量子井戸のキャリヤ吸い込み

In this project, we have studied dynamics of exciton localization and correlation between localization and exciton transfer perpendicular to the superlatticelayers by means of the picosecond time-resolve spectroscopy. We have used GaAs/AlAs short-period superlattices with a an enlarged well (SQW) which is intentionally introduced.In order to perform time-resolved spectroscopy, we have installed a time-correlated single photon counting apparatus including a constant fraction discriminator and a fast timing amplifier. We could obtain 50ps time-resolution using this photon counting system and a mode-locke Nd:YAG laer.We have performed time-resolved photoluminescence experiments in GaAs/AlAs short-period superlattices(SPS). We have found, for the first time, the tunneing-assisted recombination of electrons and holes in different wells of SPS with thin barriers. It is also found that the direct correlation between the carrier flow from SPS and the carrier sink into SQW.Perpendicular transport is strongly dependent on the barrier thickness. Varying the barrier thickness from 0.9nm to 1.8nm, we have observed the increase in the tunneling transfer and then the formation of the miniband state for the thiner barrier.In coclusion, picosecond time-resolved spectroscopy of GaAs/AlAs short-period superlattices gives us some important informations on the quantum confinement of carriers and excitons, i.e. the localization(two-dimensionality) and the perpendicular transport(three-dimensionality) due to the formation of Bloch states by the coupling between wells.

在这个项目中，我们通过picsecend Time-time-lime reslove speptroscopicy研究了垂直于超级曲突层的激子定位和激子转移之间的相关性动力学。我们已经使用了GAAS/ALAS短期超级晶格和一个放大的井（SQW），该井（SQW）有意引入。为了执行时间分辨的光谱，我们已经安装了一个时间相关的单个光子计数设备，包括恒定的分数鉴别器和快速的定时amplifier。我们可以使用此光子计数系统获得50PS的时间分辨率，并在GAAS/ALAS短期超晶格（SP）中进行了时间分辨的光致发光实验。我们第一次发现，在不同屏障的不同井中，电子和孔的辅助辅助重组。还发现，从SPS和载流子汇到SQW的载体流量之间的直接相关性。末端转运很大程度上取决于屏障厚度。将屏障厚度从0.9nm到1.8nm的变化，我们观察到隧道转移的增加，然后在更薄的屏障中形成小型稳态。由于井之间的耦合，垂直转运（三维）是由于Bloch态形成的。