Multimodal luminescence spectra of ion-implanted silica

Thermally oxidized SiO2 layers have been implanted by oxygen and sulfur ions up to an atomic dopant fraction of about 4 at%. The cathodoluminescence spectra of these ion implanted layers show besides the characteristic bands an identical sharp and intensive multimodal structure in the green up to near IR region. The energy step differences of the luminescence sublevels in average amount to 120 meV and indicate vibronic transitions in terms of a configuration coordinate potential model. A most probable candidate for these spectra are O-2(-) interstitial molecules, as we could demonstrate by respective configuration coordinate data. These assumptions are contrary to photonic crystal models for the multimodal spectra as well as to models of quantum size effects, both discussed recently in literature. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.