Preparation of rod shaped nickel oxide thin films by a novel and cost effective nebulizer technique

Nickel oxide thin films have been deposited from 0.3 M aqueous solution of nickel chloride onto microscopic glass substrates, which were chemically and ultrasonically cleaned before coating. The film depositions are carried out with 1 ml, 2 ml, 5 ml and 10 ml. The substrate temperature, spray rate, distance between substrate and nozzle and air flow rate were fixed at 400 degrees C, 0.5 ml per min, similar to 7 cm and 1.2 kg/cm(2) respectively after optimization of these deposition parameters. The effect of the volume of sprayed solution on structural, optical properties and surface morphology of the films was investigated using X-ray diffractrometer, UV-vis-NIR spectrometer, photoluminescence spectrometer, Raman spectrometer, scanning electron microscope and liner four probe resistivity set-up respectively. The diffraction peak along (1 1 1) plane at 2 theta = 37.2 degrees for all the films was observed. Besides this other low intensity peaks were observed along (2 0 0) and (2 2 0) Miller planes. The peaks indicated that this corresponds to cubic structure of NiO thin films. Optical transmittance and absorption spectra are recorded using a UV-vis-NIR spectrometer. When the quantity of sprayed volume increased, the transmittance decreased, consequently the band-gap energy wanes from 3.64 to 3.21 eV. From PL spectra, the samples show sharp and strong UV emission around 376 nm corresponding to the near band-edge emission of NiO under excitation of 275 nm. The surface morphology of the films was carried out using SEM to find the smooth, uniform and pin hole free surface. The composition of the films was estimated using EDAX spectrum of the films. The resistivity results show that the activation energy decreases with increase in the sprayed volume solution. (C) 2014 Elsevier Ltd. All rights reserved.