Effects of annealing treatment on the properties of CZTSe thin films deposited by RF-magnetron sputtering

Cu2ZnSnSe4 (CZTSe) thin films were deposited by RF-magnetron sputtering using a single quaternary CZTSe target. After the deposition, CZTSe thin films were annealed under different temperature ranging from 300 °C to 550 °C with a space of 50 °C. After annealing treatment, the grain size of CZTSe thin films became bigger. XRD results showed that thin films were kesterite-type CZTSe with a preferential orientation of the grown along the (1 1 2) direction of the Cu2ZnSnSe4 lattice. The average transmittance of thin films in near infrared region increased as annealing temperature increasing from 300 °C to 400 °C and decreased as annealing temperature increasing further. The CZTSe thin films annealed at 450 °C got very low resistivity. The thin film annealed at 400 °C has a band gap of 1.48 eV which is near the optimum band gap for solar cell.