Monovacancy Formation Enthalpy in Silicon

Positron-lifetime experiments have been conducted on silicon at temperatures between 300 and 1523 K. A lifetime attributable to positrons annihilating in monovacancies is directly observed above 1450 K. This lifetime has the same value as that associated with monovacancies at low temperature indicating that the character of the monovacancy is essentially independent of temperature. The results yield an activation enthalpy for neutral monovacancy formation of 3.6 ± 0.2 eV. No evidence for divacancy formation could be found.