STRUCTURAL-PROPERTIES OF OXYGENATED AMORPHOUS CADMIUM TELLURIDE THIN-FILMS

Cadmium telluride (CdTe) thin films were prepared by diode radio-frequ ency sputtering from polycrystalline CdTe targets in an atmosphere of argon, nitrogen and oxygen. The layers prepared in the presence of nit rogen gas were amorphous and their oxygen contents increased with the partial pressure of nitrogen. The evolution of the composition of the layers as a function of the nitrogen partial pressure during depositio n was followed by X-ray photoelectron spectroscopy. It is found that t he oxygen is bound to both tellurium and cadmium atoms. The surface of the CdTe thin films was also studied as a function of their exposure time to a plasma containing a mixture of nitrogen and oxygen. It is fo und that the oxygen contents of the surface increases with increased e xposure time. Also, this exposure resulted in an increase of the oxide thickness and a net decrease in the surface roughness of the films. ( C) 1997 Elsevier Science S.A.