Radiation enhanced silicon self-diffusion and the silicon vacancy at high temperatures

We report proton radiation enhanced self-diffusion (RESD) studies on Si-isotope heterostructures. Self-diffusion experiments under irradiation were performed at temperatures between 780°C and 872 °C for various times and proton fluxes. Detailed modeling of RESD provides direct evidence that vacancies at high temperatures diffuse with a migration enthalpy of H m V = (1.8 ′ 0.5) eV significantly more slowly than expected from their diffusion at low temperatures, which is described by H m V < 0.5 eV. We conclude that this diffusion behavior is a consequence of the microscopic configuration of the vacancy whose entropy and enthalpy of migration increase with increasing temperature.