Annealing temperature and stabilizer effects on morphological evolution of Cu2CoSnS4 films on thermally oxidized Si wafers via direct spin-coating

Abstract

Earth abundant copper based quaternary chalcogenide Cu2CoSnS4 (CCTS) films were processed by using nontoxic, direct solution-spin-coating process on thermally oxidized Si wafers. Monoethanolamine (MEA) stabilizer effects on chemical composition, crystalline phase, and morphology of the CCTS films were investigated. A systematic study on crystal phase, chemical composition and film morphology evolution including grain size and crack formation, corresponding to annealing condition, were performed via X-ray diffraction, FEG-SEM, and energy dispersive spectroscopy. The cracks free CCTS films were obtained at annealing temperature (T > 550 °C). The electrical properties of two-terminal CCTS devices processed at different annealing conditions were systematically analyzed by transfer length method (TLM) patterns. The lower resistivity (ρ∼39.66 Ωcm) and contact resistance (Rc∼12.3 ± 26 kΩ) for CCTS films annealed at 550 °C, as compared to low annealing temperature, were extracted and validated with CCTS film thickness and grain sizes supported by XRD and SEM studies.