Electron scattering from roughness-induced fluctuations in the donor density in ZnO surface quantum wells

Abstract

We present the theory of an ad hoc mechanism for electron scattering in heavily-doped zinc oxide (ZnO) surface quantum wells (SFQWs). We show that the carriers must be extra scattered in the in-plane from roughness-induced fluctuations in the donor density. In combination with the normal scattering from roughness-induced fluctuations in the potential barrier position, this gives rise to an effective roughness-related process, referred to as combined surface roughness (CSR) scattering. The CSR scattering is determined by both the roughness and doping profiles. The fluctuating donor density dominates CSR scattering at small angles and is important for large correlation length. The electron mobility in heavily-doped ZnO SFQWs is ruled by CSR scattering. This enables a successful explanation of the mobility data of accumulation layers near the ZnO surface at extremely high electron densities, which has not been explained so far. © 2010 American Institute of Physics.