Latest Study in Effects of Doping and Annealing on Optical-electrical Properties of Sol-gel ZnO Thin Films

• 1、Mechanical Engineering and Automation School, Northeastern University, Shenyang 110819

Abstract：The influences of doping and annealing on the optoelectrical properties of ZnO sol-gel films were reviewed from aspects of the first-principle calculations and experimental characterizations. It is shown that, by doping group III, IV and rare-earth elements, the n-type conductivity can be largely improved owing to large carriers introduced into the conduction band. The elements of group I and V replace the Zn and O atoms at the substitutional sites, respectively. This can increase the acceptor concentration and thus enhance the p-type conductivity. The ZnO films doped by single-element show higher resistance, the film conductivity can be largely enhanced by co-doping to increase the impurity solubility. The ZnO bandgap can be enlarged by doping Mg, Al, Ga or In on the cation site, while it will decrease by doping Cd. The ZnO film crystallinity and transmittance may be improved with annealing under atmospheric environment, while the vacuum annealing tends to reduce the transmittance due to high density of the oxygen vacancy. The review shows that the defects and energy levels of the ZnO sol-gel films, as well as its nanocrystals and multi-component nanocomposites, need to be further investigated.

Keywords： ZnO thin film Doping Post-annealing Optical-electrical properties Sol-gel method