Oblique Angle Sputtering of Chalcogenide Thin Absorbing Film

CuIn0.8Ga0.2Se2 (CIGS) is a chalcogenide semiconducting material used as absorbing layer in photovoltaic cell. In the present study, CIGS thin films were deposited on bare soda lime glass substrate by RF magnetron sputtering at various oblique angles. The structural, surface morphological, film surface roughness, optical, and electrical properties of CIGS thin films were studied at various oblique angles. Films were characterised by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Atomic force microscopy (AFM), UV-Vis-NIR spectrophotometer and four probe method. XRD revealed that all the deposited thin films were polycrystalline with preferred peak intensity along (112) plane. The film deposited at 0° (target- substrate parallel) exhibited larger crystallite size (28 nm) with low dislocation density (1.2×1015 lines m-2). The film surface at this angle was more compact and uniform in comparison to the films deposited at other deposition angles. The optical data revealed that the film exhibits more transparency (23%) at higher oblique angle (60°). The optical band gap of developed film was found to be 1.33 eV at 60° while 1.14 eV at 0°. Slanting morphology was observed at higher oblique angle. The electrical resistivity was following an increasing trend with rise in oblique angle.