Application of SRCBD S: SnO2 nanostructured thin films as room temperature gas and humidity sensors

The films were synthesized by the Substrate Rotation Chemical Bath Deposition method and have been characterized by various techniques. It is found that stoichiometry and band gap of SnO2 and S: SnO2 can be controlled moderately by air annealing as-deposited films and substrate temperature strongly affects the surface morphology. The comparative chemiresistive performance of films was studied for sensing applications of test gases and humidity. The sensitivity and relative sensor response of 5 ppm ethanol at room temperature were better than other test gases. The films annealed in air at 300, 400 and 450 °C for 1 h have excellent responses towards propanol, ethanol, and acetone, respectively. In general, the figure of merit of the synthesized gas sensor is found to vary from 2.8 to 24%, respectively. Annealed films at 350 °C for one hour have ultrahigh response towards humidity. Response-recovery time was found to vary as a function of annealing temperature due to the decrement in sensor impedance. Selectivity of the gas sensor for test gases was found to reach its maximum due to variation of SS+Sn\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{S}{S+{S}_{n}}$$\end{document} from 0.088 to 0.011. SRCBD has been reported to fabricate gas-humidity sensors economically with better steady and stable responses. The MOS sensor has shown ultrahigh humidity response and reasonable response at a low ppm of acetone gas at room temperature, which may be suitable as acetone breath analysis for seriously diabetic patients.