离子束刻蚀碲镉汞晶体的电学特性研究

摘要

本文利用迁移率谱分析了离子束刻蚀后的碲镉汞晶体，发现180µm的p型碲镉汞晶体在刻蚀后完全转为n型，且由两个不同电学特性的电子层组成：低迁移率的表面电子层和高迁移率的体电子层。通过分析不同温度下的迁移率谱，表明表面电子层的迁移率不随温度而变化，而体电子层的迁移率随温度的变化与传统的n型碲镉汞材料一致。不同厚度下的霍尔参数表明体电子层的电学性质均匀。另外，通过计算得到表面电子层的浓度要比体电子层高2—3个数量级。%In this paper, we study the electrical properties of ion-beam-etched Hg1−xCdxTe (x=0.236) crystal with the help of mobility spectrum analysis technique. In step-by-step chemical etching, it is shown that the p-HgCdTe is completely converted to the n-type one which includes a damaged surface electron layer with a low mobility and a bulk electron layer with a higher mobility after ion etching. The mobility spectra at different temperatures show that the mobility of the surface electrons is independent of temperature in the measurement temperature range while the bulk electrons exhibit a classical behavior of n-HgCdTe with characteristics that are strongly dependent on temperature. Hall data for different thicknesses show that the electrical properties of the bulk layer are uniform. Otherwise, the surface electron layer may be found to consist of a concentration about 2—3 order of magnitude higher than the bulk electron layer.