Abstract
The trivacancy (V 3) in silicon has been recently shown to be a bistable center in the neutral charge state, with a fourfold-coordinated configuration, V 3[FFC], lower in energy than the (110) planar one. Transformations of the V 3 defect between different configurations, its diffusion, and disappearance upon isochronal and isothermal annealing of electron-irradiated Si:O crystals are reported from joint deep level transient spectroscopy measurements and first-principles density-functional calculations. Activation energies and respective mechanisms for V 3 transformation from the (110) planar configuration to the fourfold-coordinated structure have been determined. The annealing studies demonstrate that V 3 is mobile in Si at T>200C and in oxygen-rich material can be trapped by interstitial oxygen atoms so resulting in the appearance of V 3O complexes. The calculations suggest that V 3 motion takes place via consecutive FFC/planar transformation steps. The activation energy for the long-range diffusion of the V 3 center has been derived and agrees with atomic motion barrier from the calculations. © 2012 American Physical Society.