CuIn(S,Se)2 thin films prepared by selenization and sulfurization of sputtered Cu–In precursors

CuIn(S,Se)2(CISSe) thin films have been prepared onto soda-lime-glass (SLG) substrates by selenization and sulfurization of magnetron sputtered Cu–In precursors. The results indicate that the properties of the CISSe films are strongly dependent on the post-annealing treatment. After annealing at 400 °C for 20 min, the CISSe films have formed tetragonal (chalcopyrite) crystal structure and the diffraction peaks of the films shift systematically to the left with the temperature varying from 400 °C to 500 °C. EDAX study reveals that the compositions of CISSe films are Cu0.83In1.17S1.67Se0.3, Cu0.86In1.13S1.61Se0.4 and Cu0.82In1.15S1.54Se0.49 after annealing at 400 °C, 450 °C and 500 °C, respectively. The direct optical band gaps of the films slightly decrease from 1.44 ev to 1.32 ev with the increase of the temperature from 400 °C to 500 °C, and the optical absorption coefficient is over 105 cm−1. The films annealed at 400 °C–500 °C are all found to be p-type and the resistivity is almost 10−2–10−3 Ω cm. The carrier mobility of the film at 500 °C is almost as high as 1.701 cm2/V S.

► CuIn(S,Se)2 is prepared by four-layered sputtering and selenizing processes. ► The preparation process can effectively prevent the indium loss and toxicity of H2Se. ► The high quality CuIn(S,Se)2 thin films have been obtained by the process. ► The band gap of the deposited CuIn(S,Se)2 films can be adjusted by heat treatment.