Optical characterization of Cu2ZnSnS4 thin films prepared by non-vacuum process for photodetector application

Cu2ZnSnS4 (CZTS) thin films have been successfully deposited by non-vacuum, sol-gel process on Molybdenum (Mo) coated Soda Lime Glass (SLG) substrate. The Cu, Zn, and Sn liquid precursor ratios have been pre-determined so as to achieve a Cu poor (23%) and Zn (14%) rich film with a goal to optimize absorber performance. A thermal annealing step (500°C, 60min) was performed in order to facilitate sulfurization from H2S source. The structural properties of CZTS film are determined by X-Ray Diffraction and Raman spectroscopy. We have confirmed deposition of a polycrystalline single phase (kesterite) CZTS thin film. Photoluminescence studies have been performed using an Yb:SYS laser at 534 nm and spanning room temperature (300K) and low temperature (8K) regimes in order to determine the optical band gap of the optimized CZTS absorber layer (1.24eV).