Chemisorption and sensitivity at semiconductor sensors revisited

Abstract

In this work we derived the adsorption isotherms for non-dissociative and dissociative chemisorption of oxygen on a semiconductor surface. We extended the Wolkenstein theory for dissociative chemisorption and re-examined the basis that led to currently accepted formalisms in the literature. In particular, we correctly incorporated dissociative chemisorption as a second-order reaction. We determined band bendings and adsorbate coverages for different gas pressure and doping for a typical metal-oxide used in gas sensing. Finally, consequences for the sensor conductivity and sensitivity are discussed.