Investigation of CdS passivation layers on HgxCd1-xTe

CdS thin films were deposited on sapphire substrates and on the HgxCd1-xTe epitaxial and single crystal samples by using chemical decomposition on thiourea and anodic non-aqueous sulphidation techniques, respectively. The chemical composition and depth profiles of deposited films were investigated by selected area XPS combined with Ar+ ion sputtering. Lateral homogeneity of CdS films was studied by using scanning Auger microscopy. Nearly stoichiometric CdS films were obtained on sapphire and HgxCe1-xTe. The thickness, chemical composition and sputtering rate at 2 keV ion energy were determined from XPS data. In both cases (either deposited on sapphire or on HgxCd1-xTe) the CdS films were found to be very non-homogeneous in thickness.