In2O3 and MoO3-In2O3 thin film semiconductor sensors:: interaction with NO2 and O3

Semiconductor sensors based on nanocrystalline In2O3 and MoO3-In2O3 thin films are found to be very sensitive to detecting low concentrations (100-200 ppb) of ozone and nitrogen dioxide. In this work, the sensitive layers were prepared by a sol-gel method. Mo-loading (MoO3-In2O3 samples) was performed by coprecipitation of In-Mo mixed hydroxides and subsequent drying and annealing (700 degrees C, air). A simple adsorption model for target gases (NO2, O-3) is proposed. According to this model O-2(-) and O- are the predominant species at the In2O3 surface during the ozone interaction. NO2 interaction with In2O3 is dissociative and leads to the formation of atomic oxygen species at the surface. (C) 1998 Elsevier Science S.A. All rights reserved.