Preparation and characterization of Sn doped NiO thin films by sol–gel spin coating technique

Abstract

Nickel Oxide (NiO), being a wide energy bandgap semiconductor, exhibit excellent optical, electrical and magnetic characteristics and show great application potential in various technological applications. Doping with suitable dopant is known to further enhance the intrinsic properties of NiO. Pristine and Sn-doped (2, 4, 6 and 8 mol%) nano-crystalline NiO films are deposited onto the substrates (glass) using conventional sol–gel spin coating technique. Detailed structural, optical, and photoluminescence properties are examined to comprehend the consequences of Sn doping in NiO host matrix. The XRD results reveal the formation of single phased, polycrystalline films that have cubic face-centered structure of NiO. The crystallinity and size of crystal found decreasing as increasing the Sn doping concentration. The vibrational stretching modes of Ni-O absorption band are observed from the FTIR spectra with wave number of 550–750 cm−1. The UV–visible transmittance results show that, the prepared samples of pure, 2 mol% and 4 mol%Sn doped NiO exhibit 75%transmittance within the visible region and which decreases with raise in concentration of Sn. Further, the optical bandgap of the films is evaluated using the Tauc’s relations and the optical energy bandgap values are found to be 3.47, 3.51, 3.52, 3.50 and 3.44 eV for pristine, 2 mol%,4 mol%, 6 mol%, and 8 mol% Sn doped films, respectively. The results offered that the structural and optical properties can be tailored by varying concentration of dopant; these films are the potential candidates for gas sensing and optoelectronic device applications.