Bi-self-trapped-exciton model for Frenkel defect formation in amorphous SiO2 by proton irradiation

The observed depth profile of the concentrations of the Frenkel defect (Si- Si bonds, E' centers or peroxy radicals) in amorphous SiO2 irradiated by hi gh-energy H+ ions is shown to be close to the calculated depth profile of O 2s-shell ionization as well as that of the electronic energy deposition (E ED). A new model, namely, bi-STE model is proposed: the Frenkel defect is c reated by nonradiative decay of two neighboring self-trapped excitons gener ated through O 2s-shell ionization followed by an Anger decay process. This model can explain the observed linear dependence of the Frenkel defect for mation on the EED, in contrast to the superlinear EED dependence expected f or dense electronic excitation as for focused ArF excimer-laser irradiation . [S0263-1829(99)10339-4].