Structural, morphological, optical and electrical properties of Ni-doped SnO2 thin films by pneumatic spray pyrolysis method

In this study, we used a pneumatic spray pyrolysis technique at 450°C to deposit Sn1–xNixO2 thin films (0.0 ≤ x ≤ 0.10) on glass substrates. The influence of doping content on the films structural, morphological, optical and electrical properties was investigated. Structural characterization by X-ray diffraction indicated that the rutile phase of SnO2 is present in all thin films, and crystallite sizes are estimated to be in the range of 27–47 nm. Furthermore, structural and microstructural analyses revealed that at x = 0.05, there is a solubility limit for (Ni/Sn) in the SnO2 matrix. The optical bandgap energy increases from 3.83 to 4.01 eV as the dopant content increases according to the Burstein-Moss effect. Resistivity is affected by doping and the thickness of thin films. The figure-of-merit calculated for all samples showed significant differences in the Ni–SnO2 thin films. There was a difference between the doped thin films depending on the thickness. The lowest resistivity of 1.32 ×\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times $$\end{document} 10−2 Ω cm and the maximum conductivity of 75 Ω−1 cm−1 was found at a Ni content of 2%. Seebeck coefficient of all the thin films developed had n-type conductivity, and the values of 76, 71, 133 and 69 µ V/K for Ni-doped SnO2 thin films at 0, 2, 5 and 10 at.%, respectively, were found to improve the thermoelectric properties of SnO2 by Ni doping.