Migration of O vacancies in alpha-quartz: The effect of excitons and electron holes - art. no. 134102

We have used density-functional theory and the nudged elastic-band method t o calculate migration pathways and estimated the activation energy for the diffusion of oxygen vacancies in a-quartz. While the energy barrier for the diffusion of a neutral vacancy is very high, 4.1 eV, the binding of a trip let-state exciton to the vacancy lowers the barrier to 1.7 eV and the attac hment of a hole lowers the barrier to 1.9 eV, making the vacancy mobile at commonly used annealing temperatures.