XPS analysis and characterization of thin films Cu2ZnSnS4 grown using a novel solution based route

Abstract

A new technique to grow single phase Cu2ZnSnS4 (CZTS) thin films for solar cells applications using a chemical route is presented; this consist in sequential deposition of Cu2SnS3 (CTS) and ZnS thin films followed by annealing at 550°C in nitrogen atmosphere, where the CTS compound is prepared in one step process by simultaneous precipitation of Cu2S and SnS2 performed by diffusion membranes assisted CBD (chemical bath deposition) technique and ZnS by conventional CBD technique.Measurements of X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) were used to identify the phases present in the CTS and CZTS films as well as to study their structural and morphological properties. Further, the oxidation states and the chemical composition homogeneity in the volume were studied by X-ray photoelectron spectroscopy (XPS) analysis. Oxidation states and results regarding structural and morphological characterization of CZTS films prepared using the novel technique are compared with those results obtained from single phase CZTS films prepared by sequential evaporation of metallic precursors in presence of elemental sulfur. XRD and Raman spectroscopy studies were used to verify that the CZTS films prepared by the novel method do not present secondary phases.