Removal of oxygen and reduction of carbon contamination on (100) Cd0.96Zn0.04Te substrates

Abstract

X-ray photoelectron and Auger electron spectroscopy as well as reflection high energy electron diffraction have been used to investigate the influence of heat treatment and sputtering on the oxygen and carbon contamination of the (100) Cd0.96Zn0.04Te surface. It was found that oxygen contamination can be completely eliminated from the surface at 300 degrees C in an ultra-high vacuum but not carbon. Heating at still higher temperatures decreases the carbon contamination only slightly while increasing the Zn to Cd ratio on the surface considerably. This affects the Cd0.96Zn0.04Te surface structure and hence subsequent molecular beam epitaxial growth. The authors have found that sputtering with argon ions at an incident angle ranging between 20 degrees and 60 degrees at temperatures between 200 and 250 degrees C can remove nearly all carbon contamination from the surface without destroying the (2*1) surface reconstruction.