Kesterite thin films of Cu2ZnSnS4 obtained by spray pyrolysis

Thin films of Cu2ZnSnS4 CZTS were deposited using the spray pyrolysis method as relatively fast and vacuum free method. Obtained samples were analyzed using the X Ray Fluorescence, grazing incidence X Ray Diffraction and Raman Spectroscopy techniques. Analysis showed close to stoichiometry composition of the films with kesterite type structure but poor crystalline quality and possible existence of secondary phases. To improve the quality of the films, the as prepared layers were annealed in the presence of elemental Sn and S. Comparison of the results before and after annealing showed a strong improvement of the crystalline quality and a significant reduction of concentration of secondary phases of the films without significant change of composition. The measured optical band gap is equal to 1.52 and 1.55 eV in the as prepared and annealed films, respectively. The optical absorption coefficient is found to be gt; 10 4 cm