Methane gas sensor application of cuprous oxide synthesized by thermal oxidation

Application of cuprous oxide (Cu 2 O) thin films for methane gas sensors was investigated. The Cu 2 O films were prepared by the thermal oxidation of Cu films under reduced partial pressure of oxygen. The XRD and AFM measurements were performed to investigate crystal structure and the surface properties of synthesized Cu 2 O films. According to the XRD patterns, the films had a preferred (111) orientation. Sensors were fabricated using synthesized Cu 2 O films and their sensitivity, response times, and recovery times were measured at different temperatures for different methane concentrations. The sensor exhibited a high sensitivity, a fast response time, and a fast recovery time for methane gas at an operation temperature as low as 180 °C. The Cu 2 O has unique characteristics, such as has p‐type conduction, high conductivity, and high carrier mobility. The fast and high response of Cu 2 O sensor for methane was explained as due to the increase of resistance in intrinsic p‐type Cu 2 O in the presence of methane gas. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)