Structural and Optical properties of nebulized Nickel Oxide thin films V. Gowthami, M. Meenakshi, N. Anandhan and C. Sanjeeviraja 1 * School of Physics, Alagappa University, Karaikudi-630 004, India. 1 Alagappa Chettiar College of Engineering and Technology, Karaikudi-630 004, India. *Corresponding author E-mail: sanjeeviraja@rediffmail.com Keywords: NiO thin films; Nebulizer technique; structural and optical properties. Abstract. Nickel oxide has been widely used as material for antiferromagnetic, electrochromic display and functional layer for chemical sensors. Nickel oxide thin films of various molarities were deposited using a simple nebulizer technique and the substrate temperature was fixed at 350 ◦ C. The effect of the molarity of precursor solution on structural and optical properties was studied using X-ray diffraction (XRD) and UV-Vis-NIR spectrometer techniques respectively. The band gap of the material was confirmed by photoluminescence spectrometer. It is found that increase in the molarity of 10ml volume of the sprayed solution leads to the increasing in film thickness. X-ray diffraction studies indicated cubic structure and the crystallites are preferentially oriented along (1 1 1) plane. It is also found that as the concentration of the solution increases the transmittance decreases, consequently the band-gap energy wanes from 4.0 eV to 3.2 eV. Introduction Nowadays thin film science and technology plays an important role in microelectronics, communications, optoelectronics, integrated optics and photovoltaic devices. Many transition metal oxide films exhibit an electrochromic (EC) effect as they change their optical transmittance upon charge insertion or extraction. These materials may be integrated into multilayer devices [1]. Electrochromic (EC) effect occurs in many transition metal oxide materials as well as in some organic molecules and polymers. The main advantage of an electrochromic device is that, it can regulate the throughput of solar energy using thin films. Nickel oxide (NiO) is an attractive material for use as an antiferromagnetic layer [2], p-type transparent conducting film [3], electrochromic devices [4, 5], and functional sensor layer for chemical sensors [6]. Most attractive features of NiO are excellent durability and electrochemical stability, low cost materials, possibility of manufacturing by variety of techniques. Among the electrochromic materials, nickel oxide thin film has been most produced by several techniques like spray pyrolysis, sputtering, vacuum evaporation, chemical deposition, sol-gel and pulsed laser deposition. The present work focuses on the effect of concentration of sprayed solution using simple nebulizer technique and its effect on structural and optical properties of NiO thin films. Experimental procedure The NiO films were deposited on pre-cleaned microscopic glass substrates using simple nebulizer technique. The glass substrates with dimensions of 2.5 X 1.5 cm were used for the preparation of thin films using various concentrations of solution and the substrate temperature was fixed at 350 o C. Nickel chloride hexahydrate (NiCl2.6H2O) was used as precursor, and it was dissolved in de-ionized water. This technique has some advantages over other nebulizer technique. The fine atomization was performed by hydraulic pressure without using any carrier gas and intermittent spraying. The volume of the solution for each deposition was fixed as 10 ml. The rate of nebulizer is as small as 0.5 ml per minute. The nozzle to substrate distance was fixed as 7 cm and the optimized air flow rate was 1.2 kg/cm 2 . After deposition, the films were allowed to cool slowly at the rate of 2 o C per minute to room temperature. Advanced Materials Research Vol. 938 (2014) pp 103-107 Online available since 2014/Jun/06 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.938.103 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 130.207.50.37, Georgia Tech Library, Atlanta, USA-16/11/14,18:12:36)