Synthesis of Cu-Doped SnO2 Thin Films by Spray Pyrolysis for Gas Sensor Application

Abstract

Pure and Cu-doped SnO2 thin films have been prepared by a simple and inexpensive technique namely spray pyrolysis. Films were prepared from an aqueous solution of tin chloride pentahydrate on ultrasonically cleaned glass substrates at temperature of 350oC. Doping is achieved by adding a small amount of copper chloride to the starting solution which is mixed thoroughly prior to spraying. The goal of this work is to study the influence of doping (Cu) with different wt% (1-5 wt% Cu) on the structural, optical, and gas sensing properties of Cu-doped SnO2 films. The crystallite size with pyramid type nanostructures was found to increase with increasing Cu content in the SnO2 films. Gas sensing characteristics were investigated for different target gases such as carbon monoxide, ammonia, H2S and ethanol. The films with 3% Cu content showed high response and excellent selectivity for H2S compared to other gases at room temperature. These results have been correlated with the surface chemistry and crystallite size effect resulting from Cu doping in the SnO2 thin films.KeywordsCu-doped SnO2 thin filmsspray pyrolysisgas sensor