Character of the reaction between molecular hydrogen and silicon dangling bond in amorphous SiO_2

摘要

The passivation by diffusing H2 of silicon dangling bond defects (E' centers,induced by laser irradiation in amorphous SiO_2 (silica), is investigated insitu at several temperatures. It is found that the reaction between E' centerand H_2 requires an activation energy of 0.38eV, and that its kinetics is notdiffusion-limited. The results are compared with previous findings on the otherfundamental paramagnetic point defect in silica, the non bridging oxygen holecenter, which features completely different reaction properties with H_2.Besides, a comparison is proposed with literature data on the reactionproperties of surface E' centers, of E' centers embedded in silica films, andwith theoretical calculations. In particular, the close agreement with thereaction properties of surface E' centers with H_2 leads to conclude that thebulk and surface E' varieties are indistinguishable from their reactionproperties with molecular hydrogen.