Proton radiation-enhanced self-diffusion studies were made of Si-isotope heterostructures. Self-diffusion experiments under irradiation were performed at 780C to 872C for various times and proton fluxes. Detailed modeling of radiation-enhanced self-diffusion provided direct evidence that vacancies at high temperatures diffused with a migration enthalpy of HVm = 1.8eV. This was significantly slower than expected from their diffusion at low temperatures; which was described by HVm < 0.5eV. It was concluded that this diffusion behavior was a consequence of the microscopic configuration of the vacancy, whose entropy and enthalpy of migration increased with increasing temperature.

Radiation Enhanced Silicon Self-Diffusion and the Silicon Vacancy at High Temperatures. H.Bracht, J.Fage Pedersen, N.Zangenberg, A.Nylandsted Larsen, E.E.Haller, G.Lulli, M.Posselt: Physical Review Letters, 2003, 91[24], 245502 (3pp)