Investigation of Polycrystalline CdTe Thin Films Deposited by Physical Vapor Deposition, Close-Spaced Sublimation and Sputtering

CdTe thin films, deposited on different substrate structures by physical vapor deposition, sputtering, and close-spaced sublimation, have been treated with CdCl₂ at several temperatures. The morphology of the films has been studied by atomic force microscopy, and the observations were correlated to results obtained from x-ray diffraction, cathodoluminescence, and minority-carrier lifetime measurements. The samples treated at 400 °C resulted in the best device-quality films, independent of deposition method and underlying substrate structure. For the first time, a nanograin structure was observed in CdTe sputtered samples.