Numerical simulation of the electrode geometry and position effects on semiconductor gas sensor response

In this work we have studied the coupled effects of electrode geometry and active film thickness on the sensitivity of semiconductor gas sensors to reducing gases. This study discusses a model that takes into account gas diffusion, adsorption and chemical reaction, to obtain the charge carrier concentration profile in the sensor bulk. The result is used in a two-dimensional semiconductor device simulation package to obtain the electrical conductance of the sensor in the presence of a reducing gas. Results show that all the parameters studied have an important effect on sensor response, especially when a highly reactive gas is being measured. Both electrode placement and film thickness must be considered if sensor sensitivity and selectivity are to be increased. For instance, if these parameters are chosen well, a poorly reactive gas can be detected in the presence of a highly reactive gas. (C) 1998 Elsevier Science S.A. All rights reserved.