Selenization of Cu2ZnSnS4 thin film using a Se metal-organic source for solar cell applications

Abstract

The effect of selenization temperature on the properties of Cu2ZnSn(S,Se)4 (CZTSSe) films using a Se metal-organic source was investigated. The metal-organic compound di-tert-butyl-selenide (DTBSe) was used as a Se source to selenize the Cu2ZnSnS4 (CZTS) films deposited by magnetron sputtering and crystallized by post-annealing on soda-lime glass. The selenization was conducted in the metal-organic chemical vapor deposition system and was carried out at temperature ranging from 300 to 390 °C for 30 min to prevent element loss, such as Zn, Sn. CZTS film was transformed into CZTSSe with various Se contents depending on the selenization temperature for 30 min. The crystalline properties were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy with a 514 nm laser. Energy-dispersive X-ray spectroscopy (EDS) was utilized for stoichiometric characterization. The depth profiling of thin films was measured by auger electron spectroscopy (AES) to confirm distribution of the elements. And the band gap of CZTSSe thin films measured by UV–Vis–NIR spectrometry varied from 1.5 to 0.95 eV along with content of Se.