Cathodoluminescence Decay Kinetics in Ge+, Si+, O+ Implanted SiO2 Layers

Cathodoluminescence spectra shapes and respective band decay times show no similarity between luminescence centers in different crystal and amorphous modifications of SiO2 and GeO2. On the other hand, the additionally produced red luminescence centers (650 nm) by oxygen implantation into SiO2 layers are of the same nature as in stoichiometric SiO2 and are attributed to the non-bridging oxygen hole center (NBOHC). Moreover, the elevated blue (460 nm) luminescence in Si implanted SiO2 belongs to the silicon related oxygen deficient center (SiODC) as in stoichiometric layers too. Ge implantation into SiO2 and thermal post-annealing leads to a huge violet luminescence (400 nm) with a first rapid decay of t = 24 ns followed by a slow hyperbolic decay with (t)-0.15 ... (t)-0.54. The last 10% show again an exponential decay with a mean life time t = 125 µs. This complex luminescent center is related to the GeODC center formed during the thermal treatment by Ge cluster formation