Ellipsometric Determination of CdZnTe preparation for HgCdTe MBE Growth

An in-situ spectroscopic ellipsometer has been installed on a molecular beam epitaxy system to improve control of HgCdTe growth. Using this device, in-situ analysis of composition, growth rate, and surface cleanliness have been monitored. In this work, the surface preparation and oxide desorption from a CdZnTe substrate will be analyzed. In addition to ellipsometry, in-situ reflection high energy electron diffraction and Auger spectroscopy were used to determine surface roughness and chemical composition for a chemically cleaned (211)B CdZnTe wafer. The combined analysis indicates that the substrate was brought into the MBE system slightly tellurium rich and covered with an oxide film. As the wafer was heated to 340 degrees celcius, the oxide desorbed and the tellurium concentration decreased.