Surface structure of (111)A HgCdTe

The surface of (111)A HgCdTe has been studied by reflection high-energy electron diffraction and atomic force microscopy (AFM). The as-grown liquid-phase epitaxy (LPE) surface has bilayer (3.7 +/- 0.2 angstrom) step/terrace structures, macro-steps, and cross-hatch patterns. Macro-steps occur about the [112] and are from 10-40 angstrom in height. AFM and x-ray measurements indicate the as-grown epilayer is approximate to 0.2 degrees off-cut (random polar angle) from the (111). < 110 > cross-hatch lines consistent with bilayer (step height = 3.9 +/- 0.2 angstrom) {111} slip dislocation are observed. The native oxide/carbon layer for the as-grown LPE (111)A HgCdTe is 8 angstrom. The experimental results suggest that the as-grown LPE surface approximates an equilibrium vicinal crystal structure. The 0.1% Br:ethylene glycol wet chemically etched surfaces retained the macro-step structure, but numerous small protrusions (10-100 angstrom height, approximate to 300 angstrom diameter) developed. The plasma-etched (111)angstrom HgCdTe surface is crystalline, but exhibits surface disorder and is roughened.