Preparation of CuInSe 2 thin films by pulsed-laser ablation technique using CuInSe 2 bulk crystal targets

CuInSe 2 (CIS) is expected to be applicable to the solar cell materials. We prepared CIS thin films by pulsed laser ablation technique using CIS targets and investigated the influence of the laser energy density, laser repetition frequency and substrate temperature on the fabrication of CIS thin films. The characterization of CIS thin films were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe micro-analyzer (EPMA). Further, as-deposited CIS thin films were annealed in Se vapor in order to improve the crystallinity of CIS thin films. We obtained CIS single phase thin films deposited at laser repetition frequency of 10 Hz and deposition time of 120 min. It confirmed that crystallinity in CIS thin films is improved by increasing substrate temperature. In particular, CIS thin film deposited at substrate temperature of 600 degrees Celsius showed a good crystallinity and smooth surface morphology and few droplets. From the results of optical absorption spectra of CIS thin film deposited at 600 degrees Celsius, it showed high absorption coefficient of the order of 10 4 to approximately 10 5 cm -1 in the wide range of wavelength and determined optical band gap Eg equals 1.0 eV. It is found that crystallinity and chemical composition of CIS thin films improved by annealing in Se vapor. CIS thin films was constructed with column-like grains which were grown by annealing.