Characterization of Cu(In,Ga)Se2 thin films prepared via a sputtering route with a following selenization process

Cu(In,Ga)Se2 films were prepared via a sputtering route with a following selenization process. In, CuIn, and Cu3Ga were observed in the precursor films. Selenization at 450 oC yielded monophasic Cu(In,Ga)Se2 films. The diffraction angles of the (112) peaks shifted toward high angles, and a uniform morphology of the obtained films was observed with high-temperature selenization. The amount of gallium ions incorporated into indium ions increased with the temperature. The probable formation mechanism of the sputtering-derived Cu(In,Ga)Se2 was proposed. Firstly, selenium species diffuse into the precursor films to form Cu(In,Ga)Se2 and Cu2−xSe phases. Subsequently, the complete reaction of selenium with residual species leads to the formation reaction of single-phased Cu(In,Ga)Se2. An efficiency of 8.34% was achieved for the fabricated solar cell.