Preparation of Cu_2ZnSnS_4 thin films by sulfurization of metallic precursors evaporated with a single source

摘要

In this study, Cu_2ZnSnS_4 (CZTS) thin films were prepared on Mo-coated soda-lime glass substrates by sulfurization of precursors deposited by single-source evaporating the metallic mixture of Cu-Zn-Sn. The influences of the composition ratio of evaporation sources and sulfurization temperature on the properties of CZTS thin films were investigated. The morphology, composition and structure of CZTS thin films were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman scattering, respectively. The XRD patterns revealed that CZTS films from both Cu-rich and Cu-correct evaporation sources contained a Cu_(1.96)S phase, whereas films from Cu-poor evaporation sources showed no secondary phase and exhibited kesterite structure with a (112) plane preferred orientation. This identification was further confirmed by a Raman spectroscope. In addition, the results of XRD patterns and SEM images showed that the crystalline quality and surface morphology of CZTS thin films were greatly improved by increasing the sulfurization temperature. The CZTS thin films possessing a near-stoichiometric composition, homogeneous surface morphology and a single CZTS phase were fabricated using a Cu-poor evaporation source at the sulfurization temperature of 550°C, and it is suitable for CZTS based high performance solar cells as absorber.