Effects of annealing on surface passivation of P-Type Hg 1-x Cd x Te grown by LPE

Abstract

Experiments were designed for analyzing effects of annealing on surface properties of P-type Hg 1-x Cd x Te Liquid Phase Epitaxy (LPE) films. Owing to special surface characteristics of P-type Hg 1-x Cd x Te material, it is necessary and vital to obtain good passivation layer for both high performance photoconductive type and photovoltaic type Hg 1-x Cd x Te detectors. Variable magnetic-field Hall measurement was used to investigate surface properties in temperature range from 1.5 to 200 K for the annealed and unannealed samples. Different temperature behavior of Hall coefficient (R H ) was observed for the two kinds of samples. Surface electrons were observed existing for unannealed samples judging by the low temperature characteristic of R H (below 10k). In addition to this, C-V measurement of MIS devices made of same annealed and unannealed sample was also used to analyze the effects of annealing. In the C-V measurement applied bias to which annealed samples could bear was larger than that to unannealed one. Meanwhile, fixed charge density in passivation layer of the annealed samples was smaller than that of the unannealed samples. The above results implied surface charge density on the surface of p-Hg 1-x Cd x Te material was reduced by annealing treatment comparing with that without annealing. On conclusion, annealing improved surface status of P-type Hg 1-x Cd x Te material.