Gas Sensing Properties of MoO3 Thin Film Deposited Using Chemical Vapor Transport of MoO3(OH)2

Abstract

Mo03 thin film has strongly attracted attention as a conductance-type gas sensor because of bigh sensitivity to various gases such as NOx, CO, H2, and NH3 in the temperature range of 300-600oC. There are many deposition techniques for Mo03 film such as thermal evaporation, sputtering, chemical vapor deposition，and pulsed laser deposition. Characteristics of films are dominated by deposition technique and its parameters, so that a challenge of new approach is required as well as extensive studies of structural and physical properties to obtain enhanced sensing properties. In this study, a new fabrication technique of Mo03 film for a gas sensor is suggested. Mo02 film was deposited at 5000oC in H2 by chemical vapor transport of Mo03(OH)2 during hydrogen reduction of Mo03 powder and the deposited film was annealed at 400oC in 02 to fabricate Mo03 phase. Gas sensing properties of the films were discussed relating with microstructural evaluations.