An ESR study of heavily ion-irradiated SiO2 glass

An electron spin resonance (ESR) study of ion-irradiated SiO2 glass was conducted to clarify the relationship between defect creation and chemical behavior of implanted atoms. The ESR signal characterized by g=2.0025 was mainly observed in both cases of deuterium (D+) and helium (He+) ion irradiation. The concentration of E' center was found to be less than 10% of that of the center of g=2.0025. The ESR signal intensity of the main center created by D+ was four times larger than that of He+ in low dose regime (1013-1015 cm-2). Experimental results indicate that this center is not directly created by atom displacements. Microwave power dependence and annealing property of the main center were quite similar to those of non-bridging oxygen hole center (NBOHC). A ''deuterium blocking model'' was proposed to explain the role of implanted deuterium atoms in SiO2. In this model, the implanted deuterium reacts with Si dangling bonds and inhibits ''perfect'' recovery of vacancies and allows the creation of NBOHC and/or its precursor. The proposed model gives a good explanation of the results and supports our assignment of the main signal to NBOHC. (orig.)