Characteristics of radio frequency sputtered CdxZnyTez thin film alloy and CdS/CdxZnyTez junction

CdxZnyTez is a potentially suitable compound semiconductor for a variety of applications and its large scale photovoltaic and imaging applications require the production of the material in thin film configuration. Radio frequency sputtered multilayers comprising of CdTe and ZnTe were thermally annealed at 300 degrees C to promote interdiffusion for the fabrication of CdxZnyTez thin films having different zinc proportions. The crystal structure, morphology and bandgap for each composition were evaluated using X-ray diffraction, scanning electron microscopy and UV-visible spectrophotometry. The films were found to be polycrystalline in nature and higher zinc concentration resulted in smoother film surface. The change in resistance of the films, having dark resistivities of a few tens of ohm-cm, was studied under illumination as a function of time and the film with 11% zinc exhibited the best ON- and OFF-response to illumination. Evaluation of CdS/Cd44.33Zn5.61Te50.06 junction parameters from the current-voltage characteristics showed very small reverse saturation current in picoampere range. (C) 2013 Elsevier B.V. All rights reserved.