The Optical, Electrical and Surface Differences between As-Deposited and Annealed NiO Films Produced by Ultrasonic Spray Pyrolysis

The interest in NiO lms has been growing fast due to their importance in many applications in science and technology. NiO films are an attractive material and are used common application area such as an antiferromagnetic layer, p-type transparent conducting lm, electrochromic devices and chemical sensors. Also, NiO is a good candidate for p-type semiconductor lms due to its wide band gap energy from 3.6 to 4.0 eV. In this work, NiO films have been grown on glass substrates by ultrasonic spray pyrolysis technique using NiCl 2 .6H 2 O as spraying solution. Films have been annealed at 500 °C in air during 1 h. Optical measurements of NiO film have been carried out at room temperature using a UV-VIS spectrophotometer.  Band gap of as-deposited and annealed films have been calculated by using optical method and found as 3.67 eV and 3.7 eV, respectively. Thicknesses of the films have been determined by filmetrics thin film measurement system. Surface properties of the films have been investigated with an atomic force microscope and electrical resistivity measurements have been performed by a four probe set-up. Consequently, the optical, electrical and surface differences have been determined between as-deposited and annealed NiO films produced by ultrasonic spray pyrolysis.