Influence of post-heat treatment on the properties of CuInS2 thin films deposited by an ion layer gas reaction (ILGAR)

CuInS2 thin films were deposited on glass substrates by an ion layer gas reaction technique and heat-treated at various temperatures and time. Characterization of the films was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrum (XPS), optical absorption and by Hall Effect measurements. The experiments show that post-heat treatment has an important influence on the composition, structural and physical properties of the ILGAR thin films. The complete formation of the chalcopyrite structure CuInS2 with the (1 1 2) preferred orientation occurs under 550 °C in 1 h. The film exhibits a quite smooth, dense and uniform topography and covers the glass substrate well. The direct band gap increases from 1.3 to 1.37 eV whilst the resistivity decreases from 102 to101 Ω cm with an increase of the annealing temperature from 250 to 550 °C, which demonstrates an improvement of the crystallinity.