Cu2ZnSnS4 thin films deposition by ultrasonic spray pyrolysis

Cu2ZnSnS4 (CZTS) thin films were deposited by ultrasonic spray pyrolysis technique. The substrate temperature was varied from 280 to 360 degrees C in order to investigate its influence on CZTS films properties. The deposition rate shows two activation energies 0.16 and 0.53 eV, respectively at low and high substrate temperatures. This indicates that CZTS deposition by spray pyrolysis passes by two different processes with increasing temperature substrate. The temperature 320 degrees C corresponds to the transition between these two processes. The X rays diffraction (XRD) analysis indicated that the deposited films have a kesterite hexagonal structure with (112) preferential orientation and a crystalline size, ranged from 30 to 52 nm with increasing substrate temperature. Stannate ZnSnO3 is present as a secondary phase. The presence of this secondary phase causes films optical band broadening. Broad emissions at around 1.27 eV was observed in the photoluminescence spectrum measured at 77 K, it is accompanied with a small peak located at 1.75 eV due the presence of zinc stannate phase ZnSnO3. (C) 2012 Elsevier B. V. All rights reserved.