Thickness Dependent Structural, Optical and Electrical Properties of CuIn_(0.8)Ga_(0.2)Se_2 Thin Films Deposited by Pulsed Laser Deposition

摘要

CuIn_(0.8)Ga_(0.2)Se_2 (CIGS) polycrystalline thin films have been deposited on soda lime glass substrate at different deposition time by pulsed laser deposition. The effect of thickness on structural, surface morphological, optical and electrical properties of thin films were investigated by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), UV-Vis-NIR spectrophotometer and electrical measurement unit. XRD study reveals that all deposited films are polycrystalline in nature and have tetragonal phase of CIGS. Crystallinity of CIGS films has been found to improve with increase in thickness of CIGS films as evidenced by sharp XRD peaks for (112) orientation. Grain size and rms surface roughness of CIGS films have been found to be increased with increase in thickness. All the deposited CIGS films exhibit direct band gap semiconducting behaviour with ~10~6 cm~(-1)absorption co-efficient. Optical band gap and resistivity of CIGS films have been found to decrease with increase in thickness.