The use of atomic hydrogen for low temperature oxide removal from HgCdTe

Reflection high energy electron diffraction (RHEED) patterns of HgCdTe surfaces etched with bromine methanol are diffuse with a faint ring pattern indicative of an overlayer consisting of a mixture of oxides and amorphous Te, Exposure to an atomic hydrogen flux results in a RHEED pattern indicative of a high quality, two-dimensional surface. Atomic force microscopy (AFM) measurements indicate a rms surface roughness less than 1 nm. CdTe grown on this surface at 80 degrees C maintains the streaky RHEED pattern and smooth surface as indicated by AFM. X-ray photoelectron spectroscopy measurements indicate that the etched surfaces contain both an oxide layer and a metallic Te overlayer which were removed by continued exposure to atomic hydrogen. Further exposure results in significant HgTe depletion, which appears to be a near-surface phenomenon. Preliminary device results indicate that use of atomic hydrogen is a viable approach for low temperature cleaning of etched HgCdTe surfaces.