Examination of the effects of high-density plasmas on the surface of HgCdTe

Abstract

High-density argon-hydrogen plasmas have been demonstrated to be very effective as etchants of CdTe, CdZnTe, and HgCdTe materials for focal plane array applications. Understanding the physical, chemical, and electrical characteristics of these surfaces is critical in elucidating the mechanisms of processing Hg1−xCdxTe. The ways in which these plasmas interact with HgCdTe, such as etch rates and loading, have been studied.1–11 However, little is known on how these plasmas affect the first few atomic layers of HgCdTe. In this study, the effects of high-density plasmas on the surface of HgCdTe were examined. The combination of argon and hydrogen plasma etch leaves a well-ordered, near-stoichiometric surface determined by both x-ray photoelectron spectroscopy and reflection high-energy electron diffraction (RHEED). Starting with Hg0.78Cd0.22Te, we were able to produce surfaces with x=0.4 and a RHEED pattern sharp enough to measure 2×1 reconstruction.