Synthesis and study of properties of CZTS thin films grown using a novel solution-based chemical route

This paper present a new method for growing thin films of CZTS using a solution-based chemical route; this consist in sequential deposition of Cu_2-xS, SnS and ZnS films by CBD followed by annealing in nitrogen atmosphere. The Cu_2-xS and SnS precursors were deposited by diffusion membranes assisted CBD technique and the ZnS by conventional CBD method. Diffusion membranes are used to optimize the kinetic growth through a moderate control of the release of the metal into the solution by osmosis. The optical, structural and morphological al properties of the CBD depositedCZTS films were compared with those of a reference CZTS film grown by sequential deposition of CuS, SnS and ZnS films, deposited by co-evaporation of the elemental precursors. X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the structural properties of both type of CZTS films. Optical and morphological properties were also studied by spectral transmittance, AFM (atomic force microscopy) and SEM (scanning electron microscopy) measurements. Structural characterization revealed that the evaporated samples present only the Cu₂ZnSnS₄ phase grown with tetragonal kesterite type structure, whereas the CBD deposited samples present a mixture of the Cu₂ZnSnS₄ and Cu_2-xS phases.