Effect of Nitrogen Flow Rate During Annealing on Structural and Electro-optical Properties of ITO Thin Films Deposited by Ultrasonic Spray Pyrolysis

In this study, we first fabricated ITO thin film samples on glass substrates at 300 °C temperature by ultrasonic spray pyrolysis technique. Then three different groups of samples were prepared under three different medium conditions. Some of these samples were annealed at 475 °C in an atmospheric medium and the other two group of samples were annealed at the same temperature, but in different media in which flowing N2 with 150 and 250 L/h. Structural, morphological, electric and electronic, and optical properties of these samples were determined by X-ray diffraction, scanning electron microscope, atomic force microscope, ultraviolet–visible spectrometer, and cryostat measurements. These measurements showed that increasing nitrogen (N2) flow rate in annealing improved the structural properties of the films by almost doubling crystallinity, but bandgap energy of the samples decreased. It was seen that with this increasing the N2 flow rate slightly reduced the transmittance of the films. In addition, Hall measurements have shown that the resistivity of the films decreased from 1.65×10-2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.65\times {10}^{-2}$$\end{document} to 1.19×10-2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.19\times {10}^{-2}$$\end{document} Ω cm by introducing the N2 gas. It has also been shown that annealing under N2 gas flow is a method that can be used efficiently to reduce the Oxygen (O2) ratio in the ITO thin films.