Conventional and Rapid Thermal Annealing of Paramagnetic Oxygen Vacancy Defects (E'1 Centers) in Ion Implanted Amorphous SiO2: A Uni-Molcular Recombination Process

Abstract

ABSTRACTThe irreversible thermal annealing behaviour of paramagnetic oxygen vacancy defects (E' centers) induced by 40 keV Ne+ and 140 keV Kr+ ion implantation in amorphous SiO2 has been studied by means of electron paramagnetic resonance. The reversible E'l⇆ B2 defect transformation occurring via a hole injection/trapping process under ionising radiation (190 keV H+) is used as a means of distinguishing a reversible modification of the defect charge state from irreversible annealing of oxygen vacancies. Irreversible thermal recovery is shown to occur between 500 and 900°C. Both conventional and tungsten lamp heater annealing results are compared to predictions based on Simpson and Sosin's model for diffusional recombination of spatially correlated Frenkel pairs and to a simple model for unimolecular recombination. The annealing behaviour observed is accounted for assuming a gaussian distribution in activation energy for diffusion.