Raman mapping of MoS2 at Cu2ZnSnS4/Mo interface in thin film

A Cu2ZnSnS4 (CZTS) thin film deposited on Mo contact film using direct current magnetron sputtering and sulfurized is studied. The morphological and structural investigations are focused on the interface between the CZTS film and the back Mo layer. The film is shown to be polycrystalline with an average grain size of 0.8 mu m and of a high conductivity of the grain boundaries. It is also characterized by a suitable elemental composition with a noncritical deviation from the stoichiometry across the film depth. This results in the optical bandgap of 1.48 eV, which is optimal for solar cell absorbers. Raman spectra show low FWHMs of two A-symmetry dominant bands for CZTS thin film, which confirms a high quality of the crystal structure over a large area. At the same time, ZnS secondary phase is found on the film surface, while MoS2 is detected in the depth using a resonant excitation. The Raman mapping shows a non-uniform distribution of MoS2 along the interface between the CZTS film and the back Mo layer.