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Study on the semi-insulating mechanism of undoped GaAs

无掺杂GaAs半绝缘机理研究

基本信息

批准号：
06044021
负责人：
SUEMITSU Maki
金额：
$ 1.54万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044021/
关键词：
GaAs semi-insulating point defect optical properties electron spin resonande EL2 photoquenching photoconductivity 硫化カリウム

项目摘要

We have concentrated on the study of the mechanism of the photoquenching of EL2, a most important point defect in undoped semi-insulating GaAs. The photoquenching effect is a phenomenon in which all optical and electrical properties of EL2 are vanished by being irradiated with near-infrared lights at T<90K.The effect has been attributed to a transition of the EL2 defect into a metastable state, while some recent reports suggest contributions from other point defects than EL2. The clarification of the photoquenching effect is therefore of great importance in realizing high-quality GaAs crystals. What we found this year is as follows.(1)The photoquenching of EL2 does not occur by itself. Contributions from other defects are essential. By testing a series of samples, in which only the carbon acceptor concentration is varied, we found a strong influence of the carbon acceptor on the activation of the photoquencing effect.(2)By a quantitative analysis of the temperature dependence of the EL2 photoquenching, we found that a deep acceptor located at 70-80 meV above the valence band plays an essential role in the photoquenching effect.(3)This level, named actuator level, accounts for both the carbon-concentration and the temperature dependence of the photoquenching effect, by assuming that the actuator level triggers the photoquenching of EL2 when it is neutral and triggers the photorecovery of EL2 when it is negatively ionized.(4)By thermally-stimulated-current(TSC)measurements, we have confirmed the presence of a deep acceptor at the relevant position in the bandgap. Its charge state became neutral from the original ionized one after irradiation with the quenching light, consistent with our actuator level model.

我们专注于EL2光猝灭机制的研究，EL2是未掺杂半绝缘GaAs中最重要的点缺陷。光猝灭效应是一种现象，其中EL2的所有光学和电学特性在T<90K的近红外光照射下消失。这种效应被归因于EL2缺陷向亚稳态的转变，而最近的一些报告表明EL2以外的其他点缺陷也有贡献。因此，阐明光猝灭效应对于实现高质量的GaAs晶体非常重要。我们今年的发现如下：(1)EL2的光猝灭现象不会自行发生。其他缺陷的贡献也是必不可少的。通过测试一系列仅改变碳受体浓度的样品，我们发现碳受体对光猝灭效应的激活有很强的影响。(2)通过对EL2光猝灭的温度依赖性的定量分析，我们发现位于价带上方70-80 meV的深受体在光猝灭效应中起着至关重要的作用。(3)这个能级，称为致动器能级，解释了两种光猝灭效应。通过假设驱动器能级在中性时触发EL2的光猝灭，并在负电离时触发EL2的光恢复，研究了光猝灭效应的碳浓度和温度依赖性。(4)通过热刺激电流(TSC)测量，我们证实了在带隙中相关位置存在深受体。在淬灭光照射后，其电荷状态从最初的电离状态变为中性，这与我们的执行器能级模型一致。