Structural and electrical properties of spray deposited thin films of CuInS2 nanocrystals

Nanocrystalline thin films of CuInS2 were grown onto ultra clean glass substrates using the spray pyrolysis technique. The films were characterized by X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and resistivity measurement. XRD pattern, SEM and TEM micrographs show that the films grown at about 300 degrees C are made up of single phase nano-sized (12-15 nm) particles of CuInS2. Using Williamson-Hall equation, crystallite size and lattice strain of the film were estimated with the broadening of XRD peaks. EDX of nanoparticles dispersion confirmed the presence of elemental CuInS2 and no peaks of impurity have been detected. The temperature dependence of resistivity of CuInS2 thin films, determined in the temperature range of 100-300 K, exhibits their semiconducting behavior. The films showed the activated variable range hopping (VRH) in the localized states near the Fermi level. (C) 2011 Elsevier B.V. All rights reserved.