Gas sensing properties of MoO3 film fabricated using shemical vapor transport of MoO3(OH)2

Abstract

Recently, semiconducting MoO3 film has strongly attracted attention as a conductance-type gas sensor because of high sensitivity to various gases such as NOx, CO, H2, and NH3 in the temperature range of 300-600oC. There are diverse deposition techniques for MoO3 film such as thermal evaporation, sputtering, chemical vapor deposition, electrodeposition, and flash evaporation. The characteristics of the 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 MoO3 film for a gas sensor, which is accomplished by chemical vapor transport of MoO3(OH)2 during hydrogen reduction of MoO3 powder, is suggested. MoO2 film was deposited at 550oC in H2 atmosphere and the deposited film was oxidized at 600oC in air environment to fabricate MoO3 phase. Electrical properties and gas sensing characteristics of the films were discussed relating with microstructural evaluations.