Effects of Annealing Temperature on Structural and Optoelectronic Properties of Cu2ZnSnS4 Thin Films

[[abstract]]The sol-gel method was used to prepare Cu2ZnSnS4 (CZTS) films on quartz glass substrates, and then annealed under controlled argon atmosphere of temperature 250~350 ℃ for 1 hour. For the purposes of this study, we identified the effects of annealing temperature on the crystal structure, surface morphology, cross-sectional structure, chemical composition, optoelectronic properties of the CZTS films. As identified through analysis, the films were of the Kestenite-Cu2ZnSnS4 structure, and no secondary phase was observed, regardless of the changes of the annealing temperature. As the annealing temperature increased, the average grain sizes of the films increased, while the plate-like and fibrous microstructures grew and the sulfur contents decreased in the films. The CZTS film annealed at 325 ℃ had the better absorption coefficient up to about 0.94×104 cm-1, and its resistivity value and direct energy gap value were measured as 4.35 Ω cm and 1.39 eV, respectively. The CZTS film annealed at 300 ℃ possessed relatively lower resistivity value of 3.92 Ω cm, and had a direct energy gap value of 1.43 eV