Gas sensors based on semiconductor oxides: basic aspects onto materials and working principles

摘要

The properties of the most important semiconductor oxides for gas sensing, such as SnO_2, TiO_2, WO_3 and their modifications due to ion-addition or to catalyzers, have been reviewed. The oxide powders, synthesized via wet chemical routes, have been characterized both as dispersed powders and as sintered films. Deposition of thick film gas sensors was carried out through screen-printing technology. They have been studied comparing the electrical behavior under identical environmental conditions. Potential barrier heights have been measured via stimulated temperature measurements and density of ionized donors obtained via Hall Effect. A theoretical model has been developed to justify the size dependent behavior of nanocrystalline oxides.