Deposition and characterization of Cu2SnS3 thin films by co-evaporation for photovoltaic application

Cu2SnS3 (CTS) is a p-type direct band gap ternary compound semiconductor. Its constituent elements are non-toxic, abundant in earth crust and low cost. We report the deposition of Cu2SnS3 thin films on soda-lime glass substrate by co-evaporation technique at different substrate temperatures. The effect of substrate temperature on the growth of CTS thin films has been investigated. X-ray diffraction study confirms the formation of tetragonal phase of Cu2SnS3. The Raman analysis confirms the ternary/binary phases of the CTS thin films. The surface morphology of the film is examined by atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) has been used for analyzing the film composition. The X-ray photoelectron spectroscopy (XPS) shows that Cu, Sn and S are in the oxidation states of +1, +4 and −2 respectively. The optical band gap of CTS thin films is 1.23 eV and the absorption coefficient is the order of 105 cm−1. Hall measurements confirm the p-type nature of the as-prepared CTS films. The carrier concentration, resistivity and mobility are 2.81×1021 cm−3, 1.31×10−3 Ω cm and 1.70 cm2 V−1 S−1 respectively.