Effect of thermal pretreatment of metal precursor on the properties of Cu2ZnSnS4 films

Zn/Sn/Cu (CZT) stacks were prepared by RF magnetron sputtering. The stacks were pretreated at different temperatures (200 degrees C, 300 degrees C, 350 degrees C, and 400 degrees C) for 0.5 h and then followed by sulfurization at 500 degrees C for 2 h. Then, the structures, morphologies, and optical properties of the as-obtained Cu2ZnSnS4 (CZTS) films were studied by x-ray diffraction (XRD), Raman spectroscopy, UV-Vis-NIR, scanning electron microscope (SEM), and energy-dispersive x-ray spectroscopy (EDX). The XRD and Raman spectroscopy results indicated that the sample pretreated at 350 degrees C had no secondary phase and good crystallization. At the same time, SEM confirmed that it had large and dense grains. According to the UV-Vis-NIR spectrum, the sample had an absorption coefficient larger than 10(4) cm(-1) in the visible light range and a band gap close to 1.5 eV.