Physical properties evolution of sprayed Cu2MgSnS4 thin films with growth parameters and vacuum annealing

Quaternary chalcogenide Cu2MgSnS4 (CMTS) thin films were grown by spray pyrolysis technique on glass substrates using methanol as solvent. CMTS thin films growth methodology has been based on three steps in order to optimize structural and optical properties. X-ray diffraction, Raman spectroscopy, Spectrophotometer and SEM were used to investigate physical properties of CMTS thin films. The first step was searching for optium substrate temperature by performing synthesis of CMTS thin films at different temperatures (250, 200, 175 and 150 degrees C). Structural analysis has shown that the best grain size was found for thin films deposited at 175 degrees C but with presence of secondary phases. The second step was a simultaneous decrease in solvent volume, sulfur and copper concentrations in order to remove undesirable phases. The third step was a vacuum annealing of CMTS thin films at different temperatures 225, 300, 375 and 450 degrees C for 1 h in order to improve more physical properties. XRD analysis have shown that vacuum annealing at 450 degrees C temperature has eliminated completely secondary phases and increased grain size up to 51.82 nm. During these steps, band gap energy has been varied from 1.33 eV to a maximum value of 1.91 eV with an absorption coefficient a value near 10(5) cm(-1). These experimental results have shown that CMTS thin film was successfully grown by spray pyrolysis technique and can be considered as promising absorber for photovoltaic applications.