Theoretical model for nanocrystallite size dependent gas sensitivity enhancement in nanocrystalline tin oxide sensor

A new theoretical model has been proposed, which can satisfactorily explain the reported experimental data of the nanocrystallite size dependence of the gas sensitivity of nanocrystalline pure tin oxide (SnO2) thin film sensor. According to the proposed model, the gas sensitivity of nanocrystalline pure-SnO2 thin film sensor is directly proportional to the ratio 2d/D, where 'd' and 'D' are the space-charge layer thickness and the nanocrystallite size, respectively. The model suggests that gas sensitivity is enhanced drastically when the nanocrystallite size is less than twice of the space-charge layer thickness, which is in excellent agreement with the reported experimental behavior.