Gas Sensors Based on TCO Thin Films

Professor Seyed Mohammad Rozati
Physics Department
University of Guilan
Guilan, Iran

A fundamental role is played by highly transparent conducting oxide (TCO) thin films in science and technology. Materials such as oxides of tin, indium, zinc and cadmium and their various alloys, have been extensively studied and applied as electrodes in thin film technologies. These materials possess a wide energy band gap (Eg>3eV) and are therefore transparent in the visible region, where the long wavelength cutoff depends on the charge carrier concentration. Structural factors are important during the design of TCO for gas sensor. In the case of thin films, it was shown that structural engineering of sensing materials could be used for the optimization of sensing parameters as gas sensitivity, selectivity, and time response. It is well known that the physico-chemical properties that control gas adsorption on to the surface of a TCO can greatly influence its electrical conductivity. A highly selective and easy to use alcohol sensor has always been in great demand in biomedical, chemical, and food industries, more recently in an electronic nose. We present the preparation of a TCO gas sensor based on porous nanostructured thin films using spray pyrolysis technique.