Characterization and preparation of Sn-doped CuGaS2 thin films by paste coating

The Sn-doped CuGaS2 thin films were fabricated by paste coating and annealing. The paste was prepared by ball milling the mixture of Cu2S, Ga2S3 and CuS. The precursor layers were deposited on the glass-substrate through the spin-coating, and then annealed in argon atmosphere at 600 °C for 20 min. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray analysis (EDAX) and UV-vis spectrophotometer were used to characterize the Sn-doped CuGaS2 thin films. The analysis of the XRD patterns revealed that the prepared thin films had a single-phase chalcopyrite structure. With the increase of Sn concentration, the diffraction angle of (112) peak was decreased. Moreover, the band gaps of Sn-doped CuGaS2 thin films were 2.41 eV (0.0 at% Sn-doped), 2.01 eV (0.41 at% Sn-doped) and 1.87 eV (1.15 at% Sn-doped).