Observed depth profiles of the concentrations of Frenkel defects (Si-Si bonds, E' centers or peroxy radicals) in amorphous material, after bombardment with high-energy H+ ions, were shown to be close to the calculated depth-profile of O 2s-shell ionization as well as that of the electronic energy deposition. A new model was proposed in which the Frenkel defect was assumed to be created by the non-radiative decay of 2 neighboring self-trapped excitons which were generated through O 2s-shell ionization; followed by an Auger decay process. This model could explain the observed linear dependence of Frenkel defect formation upon the electronic energy deposition; in contrast to the supra-linear electronic energy deposition dependence which was expected for dense electronic excitation, as in the case of focussed ArF excimer laser irradiation.

Bi Self-Trapped Exciton Model for Frenkel Defect Formation in Amorphous SiO2 by Proton Irradiation. N.Matsunami, H.Hosono: Physical Review B, 1999, 60[15], 10616-9