Fabrication of Cu(InGa)Se2 thin-film solar cells grown with ionized Ga source

Polycrystalline Cu(InGa)Se₂ (CIGS) thin films have been grown onto a soda-lime glass substrate by the co-evaporation process using ionized Ga. It was found from the XRD and Raman measurements that the crystallinity of the films grown with ionized Ga was equivalent to the films grown with normal Ga. In addition, a reduction of defect densities measured by the admittance spectroscopy and the improvement of the reverse saturation current assessed by the I-V characteristics were observed in the films grown with ionized Ga, implying an improvement of film quality. Furthermore, an enlargement of grain size was shown. Finally, the CIGS solar cell with a promising efficiency of 15.1% has been achieved by using the ionized Ga source.