Influence of substrate temperature on the structural and optical properties of crystalline ZnO films obtained by pulsed spray pyrolysis

In this work, we report on the structural and optical properties of ZnO films deposited by pulsed spray pyrolysis at relatively low temperatures, compatible with a large variety of substrates and processing technologies. Crystalline ZnO films were deposited onto glass substrates using zinc acetate dihydrate dissolved in distilled water with concentration of 0.2M. The temperature of the substrate was varied in the range T-s=473-673K with ?=50K. Effect of T-s were investigated by scanning electron microscopy, x-ray diffraction and energy dispersive x-ray, and optical spectroscopies. Also, the influence of T-s on the grain size, phase composition, texture quality, coherent scattering domain size, crystal lattice parameters, chemical composition, transmission coefficient, and the bang gap of the ZnO films were studied. X-ray diffraction analysis revealed that films were polycrystalline with hexagonal phase and showed as preferential orientation (101) at T-s<573K and (100) and (002) at T-s>573K. Scanning electron microscopy (SEM) measurements showed that the substrate temperature has a strong effect on morphology of the films. Energy dispersive analysis revealed that ZnO films consisted of the non-stoichiometric compounds. Optical measurements showed ZnO films to be highly transparent in the visible region, and optical band gap is shifting from 3.18eV to 3.30eV. Copyright (c) 2015 John Wiley & Sons, Ltd.