Evidence of bandbending flattening in 10 nm polycrystalline SnO2

We developed a model for n-type metal-oxide semiconductors, which allows one to calculate the density of charged surface states on nanostructured grains, once the Schottky barrier height is known.We characterised structurally and electrically two sets of polycrystalline SnO2 films with average grain radius of 30 and 10 nm. The purpose of this experiment was to observe the flattening of the bandbending and the corresponding decrease in the density of charged surface states which are, in turn, responsible for the pinning of the Fermi level. Finally, we highlighted how this phenomenon affects the characteristics of the films as gas sensors.