Substructural investigations, Raman, and FTIR spectroscopies of nanocrystalline ZnO films deposited by pulsed spray pyrolysis

Nanocrystalline ZnO films were deposited onto glass substrates in the temperature range of 473-673 Kusing pulsed spray pyrolysis. The structural, substructural, and optical properties of the films were investigated by means of X-ray diffraction analysis, Raman scattering, and Fourier transform infrared (FTIR) spectroscopy. The effect of the substrate temperature (T-s) on the coherent scattering domain (CSD) sizes L, microstrains epsilon, and microstress sigma grades, and the average density of dislocations rho in the films were estimated through the broadening of X-ray lines using the Cauchy and Gauss approximations and the threefold function convolution method. The ZnO films grown at T-s = 623-673K possessed the highest values of L, and the lowest of epsilon, sigma, and rho, indicating high-crystalline quality. The Raman spectra showed peaks located at 95-98, 333-336, 415, 439-442, 572, and 578-584 cm(-1), which were interpreted as E-2(low) (Zn), (E-2(high)-E-2(low)), E-1(TO), E-2(high)(O), A(1)(LO) and E-1(LO) phonon modes of the ZnO wurtzite phase. The FTIR spectra showed relatively weak signals at 856, 1405, and 1560 cm(-1), corresponding to the C-H and C-O stretching modes, in addition to the main Zn-O mode at 475 cm(-1), indicating a low content of precursor residues. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim