Transport and surface conductivity in ZnO

Control of the electrical properties of ZnO is difficult to achieve. Doping is affected by the presence of a n-type background. Magnetotransport measurements can extract detailed information on donors and acceptors, but characterization is complicated by effects such as the surface conductivity. This conducting layer can be activated by ambient illumination or by heating in the absence of oxygen. There are considerable differences in the behavior of the various polar and nonpolar crystal faces. This paper provides an overview of the properties of ZnO surface conductivity, as well as the methods which have been implemented to account for it while interpreting carrier transport measurements.