Relationship between residual strain and band gap of Cu2ZnSnS4 thin films grown by pre-sulfurized precursor

Abstract

In this study, we focus on the residual stress and band gap change of Cu2ZnSnS4 (CZTS) thin films fabricated using a pre-sulfurized precursor, which contained sulfur compounds such as ZnS, SnS2, and Sn3S4. The residual strains of the CZTS thin films fabricated using the pre-sulfurized precursor (type-A) are smaller than those of films (type-B) fabricated using a Cu/Zn/Sn layer metal precursor. The type of residual stress, compressive or tensile, was determined by the sulfurization temperature of the CZTS thin film. The band gaps of the type-A samples exhibited less deviations from the value of 1.50 eV, which is the well-known band gap of CZTS, compared to those of the type-B samples.