Effects of Cu doping on nickel oxide thin film prepared by sol-gel solution process

We prepared nickel oxide (NiO) thin films with p-type Cu dopants (5 at%) using a sol-gel solution process and investigated their structural, optical, and electrical characteristics by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmittance and current-voltage (I-V) characteristics. The crystallinity of the NiO films improved with the addition of Cu dopants, and the grain size increased from 38 nm (non-doped) to 50 nm (Cu-doped). The transmission of the Cu-doped NiO film decreased slightly in the visible wavelength region, and the absorption edge of the film red-shifted with the addition of the Cu dopant. Therefore, the width of the optical band gap of the Cu-doped NiO film decreased as compared to that of the non-doped NiO film. The resistivity of the Cu-doped NiO film was 23 Omega m, which was significantly less than that of the non-doped NiO film (320 Omega m). Thus, the case of Cu dopants on NiO films could be a plausible method for controlling the properties of the films. (c) 2014 Elsevier GmbH. All rights reserved.