Chemisorption and sensitivity at semiconductor sensors revisited

•Extension of Wolkenstein theory to dissociative chemisorption on a semiconductor surface is discussed.•Band bending and adsorbate coverage for different oxygen pressure and doping in tin oxide are derived.•Consequences for the sensor conductivity and sensitivity are dicussed. 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.