Growth and Properties of Sprayed CZTS Thin Films

In the present study, we have synthesized single phase nanocrystalline Cu2ZnSnS4 (CZTS) thin films using the spray pyrolysis technique. The films were grown on glass substrates at 300°C and were subsequently vacuum annealed for 1 h, at different temperatures ranging from 350°C to 500°C. X-ray diffraction (XRD) studies show that the films crystallize in the CZTS kesterite structure belonging to the tetragonal system. Atomic force microscopy and scanning electron microscope studies together with XRD show that the as-grown and annealed films are made up of nano-sized (below 15 nm) particles of CZTS. Secondary ion mass spectrometry shows that the films have uniform composition along the depth except for a thin surface layer which is slightly lower in Cu content. Optical studies show that the optical band gap values are in the range reported for thin film CZTS.