Growth of CuInTe2 polycrystalline thin films

Abstract

The coevaporation of elements is one of the most successful techniques to deposit polycrystalline chalcopyrite thin films for photovoltaic applications. The morphology of CuInTe2 thin films and different growth mechanisms depending on the chalcogen rates during deposition are presented. The tellurium rate turned out to be the most important parameter influencing the morphology of CuInTe2 thin films. A low tellurium rate has several effects on the film morphology in In-rich areas: For slightly In-rich films the grain size increases and the crystallites are well (112) oriented, for strongly In-rich films the morphology changes to oriented cuboids with tetragonal symmetry. Energy dispersive spectroscopy (EDS) measurements proved, that the film composition follows the pseudobinary tie line i.e. Cu2TeIn2Te3 for a wide range of copper to indium ratios. X-ray diffraction (XRD) measurements showed the presence of Cu2Te as secondary phase in Cu-rich films and the defect chalcopyrite CuIn5Te8 in strongly In-rich films.