Transport and gas sensing properties of In2O3 nanocrystalline thick films: A Hall effect based approach

Undoped nanosized In2O3 with n-type conduction was produced in both polymorphic forms (cubic and rhombohedral) and deposited by screen-printing as thick films. These films show high sensitivity to low O3 concentration levels. They have been investigated by four point conductance and Hall effect measurements under sensor operating conditions (elevated temperature and ozone exposure). The effective values of the charge carrier concentration and mobility have been calculated from the experimental records using the recipe for the single crystals. The response to O3 is discussed in the frame of the standard models for gas sensors. The observed deviations from the model are explained in connection with the film crystalline structure and microscopic parameters spread.