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 (T-s) 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 T-s = 350 degrees C), tetragonal structure (at T-s = 400 degrees C), and monoclinic structure (at T-s = 450 degrees C). A phase change from monoclinic CTS to orthorhombic Cu3SnS4 was observed at T-s = 500 degrees 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 degrees C to 500 degrees 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 degrees C could be used as an absorber layer for the application of thin film solar cells.