Sulfurization temperature dependent physical properties of Cu2SnS3 films grown by a two-stage process

Cu2SnS3 (CTS) is a promising absorber for thin film solar cells because of its suitable opto-electronic properties. This article reports the effect of sulfurization temperature (Ts) on the physical properties of CTS thin films deposited by two-stage process. X-ray diffraction and Raman analyses revealed that sulfurized CTS films exhibited different polymorphic forms, such as triclinic structure (at Ts = 350 °C), tetragonal structure (at Ts = 400 °C), and monoclinic structure (at Ts = 450 °C). A phase change from monoclinic CTS to orthorhombic Cu3SnS4 was observed at Ts = 500 °C. The AFM results confirmed that the sulfurized films had the smooth surface without pinholes. The optical band gap was varied in the range, 2.34-1.49 eV with increasing sulfurization temperature from 150 °C to 500 °C. All the sulfurized films showed p-type conducting nature. The obtained results indicated that single phase CTS films prepared in the temperature range of 400-450 °C could be used as an absorber layer for the application of thin film solar cells.