A comprehensive investigation was made of zinc vacancies and interstitial diffusion in ZnO using ab initio total energy calculations within local density approximation and the generalized gradient approximation. The zinc interstitial was found to diffuse efficiently, with a barrier of 0.3 to 0.5eV. Diffusion perpendicular to the c-axis tended to occur via an interstitial mechanism, and diffusion parallel to the c-axis tended to occur via a kick-out mechanism. The diffusion of the zinc vacancy was found to be isotropic, and the migration barrier of the zinc vacancy was about 1.0eV. According to these results, zinc vacancies were responsible for zinc self-diffusion in n-type ZnO.

First-Principles Study of Diffusion of Zinc Vacancies and Interstitials in ZnO. Huang, G.Y., Wang, C.Y., Wang, J.T.: Solid State Communications, 2009, 149[5-6], 199-204