Abstract:

Cu3SnS4 thin films were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) method at room temperature and annealed at different temperatures in the nitrogene atmosphere to investigate the effects of the post-deposition annealing process on the structural and optical properties of the films. Structural, surface morphological, and optical properties of films were analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results revealed that the films consisted of a tetragonal Cu3SnS4 phase before annealing, and increasing annealing temperature caused the improvement of crystal structure and the formation of Cu4SnS4, Cu2S and CuS secondary phases. SEM images showed that the films were composed of nanometer-sized randomly shaped particles. EDAX measurements revealed the existence of Cu, Sn and S elements and also showed that the amounts of Sn and S elements decreased with increasing annealing temperature. Raman spectra confirmed the formation of the Cu3SnS4 phase and secondary phases of Cu4SnS4, Cu2S and CuS at high annealing temperatures. From optical absorption measurements, it was determined that the films had direct transitions and the band gap energies decreased from 1.62 eV to 1.47 eV with increasing annealing temperature.