Characterization of CdTe-Sb co-sputtered films

Abstract

The structure and electrical properties of CdTe-Sb co-sputtered thin films and their relation with composition were studied. The films were grown on glass substrates by radio frequency sputtering deposition. The ternary alloys were deposited by co-sputtering of Sb and CdTe. The substrate temperature was varied from room temperature to 250 °C. The composition measurements show that the Sb content in the films ranges from 8 to 60 at. %, depending on the area fraction covered by the Sb attached to the CdTe target. The Sb content is found to be independent of the substrate temperature. The structure of the films was determined from x-ray diffraction measurements. Three kinds of structures were observed, depending on the Sb content and substrate temperature: (1) CdTe polycrystalline films containing small amounts of Sb, that is probably incorporated in the Cd and Te sites of the CdTe lattice; (2) amorphous CdSbTe films, with high Sb content and low substrate temperatures; and (3) polycrystalline films composed by a mixture of both Sb and CdTe crystallites, with high Sb content and high substrate temperatures. The room temperature electrical resistivity of the films varies from 109 Ω cm in the CdTe polycrystalline films to 10−3 Ω cm in the films composed of Sb and CdTe crystallites.