Comparative study of structural and morphological properties of nanostructured CuIn_(2n+1)S_(3n+2) (n = 0, 1 and 2) thin films produced by oblique angle deposition

摘要

CuInS_2, CuIn_3S_5 and CuIn_5S_8 films were grown by thermal evaporation using oblique angle deposition technique. During the deposition, the substrate temperature was maintained at T_s = 150℃ and the deposition angle was fixed at α = 0? and 85?. The powders and thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). From the XRD data of powders, we calculated the lattice parameters of the structure for the different compounds. XRD patterns of thin films revealed that all samples deposited at α = 0? were polycrystalline. Indeed, CuInS_2 and CuIn_3S_5 films had a chalcopyrite structure with preferred orientation along (1 1 2) while CuIn_5S_8 films exhibit a spinel structure with preferred orientation along (3 1 1). However, CuIn_(2n+1)S_(3n+2) with n = 0, 1 and 2 films deposited at α = 85? were amorphous in nature. The surface and cross-section of the films were observed by AFM and SEM. The oblique angle deposition films showed an inclined columnar structure, with columns tilting in the direction of the incident flux. The surface roughness of the different films deposited, respectively, at α = 0? and 85? was determined by two methods (AFM and spectrophotometric analysis). The obtained values show an increase of the surface roughness by increasing the deposition angle α.