半导体异质结构中的谷间电子转移效应

TRANSFERRED ELECTRON EFFECT BETWEEN DIFFERENT ENERGY VALLEYS IN SEMICONDUCTOR HETEROSTRUCTURE

本文使用单带双谷理论研究了GaAs/AlGaAs异质结构中的谷间电子转移效应。计入每一异质结界面上的能带交错,谷间耦合和电场的贡献,导出了计算异质结构隧穿概率和隧道电流的公式。以GaAs/AlGaAs异质结构为例,算出不同结构、不同合金组分比及不同电压下的隧穿概率和隧道电流。讨论了异质结界面、势阱和势垒材料的能带结构以及外加电压对谷间电子转移效应的影响。算得的隧道电流同实验结果相符合,证实了这一理论在研究多能谷系统中的适用性。在此基础上进一步分析了这一谷间电子转移效应与熟知的Gunn效应间的区别,并讨论了它在半导体器件设计中的应用。

The transferred electron effect between different valleys in AlGaAs/GaAs/AlGaAs heterost-ructure is studied using the one band two valleys model in this paper. Taking the contributions from various electric field and the band offset and current are derived. The tunnelling probabilities and currents for various hetorostructures, alloy components and electric fields have been calculated. The dependence of transferred electron effect on the heterojunction interface, the band structures of the well and barrier materials, and the electric field is discussed. The computed tunnelling current agrees with the experimental results, and so the effectiveness of this model in the research of many valleys system is demonstrated. Furthermore, the difference between this transferred electron effect and the well known Gunn effect is pointed out and its application in the developing 9f semiconductor devices is discussed.