Author: S. Arul, R. Arun Kumar

DOI:

CuIn_0.7Ga_0.3Se₂ (CIGS) alloyed compound was prepared from the mixtures containing appropriate amounts of high quality elemental copper, indium, gallium, and selenium by direct melting.  The chemical composition and phase evolution were analyzed by x-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) measurements. High resolution transmission electron microscopy (HRTEM) micrographs show the lattice spaces of the prepared CIGS powder. Cu (In, Ga)Se₂ thin films were deposited onto well cleaned glass substrates under a vacuum of 2x10^-6 torr using hot wall deposition technique. Transmittance spectra of the prepared CIGS films were obtained in the wavelength range of 190 nm to 2500 nm using a double beam spectrophotometer. From the plot of hν versus (αhν)², the band gap of the hot wall deposited CIGS thin film is estimated to be1.18 eV by extrapolating the linear portion of the curve to the hν axis. The atomic force microcopy (AFM) images revealed that the average grain size was 20 nm and the surface roughness was about 8 nm for the prepared thin films.

Keywords: CIGS; direct melting method; absorber layer; hot wall deposition technique; thin film solar cells.