Excited states of modified oxygen-deficient centers and Si quantum dots in Gd-implanted silica glasses: emission dynamics and lifetime distributions.

The emission centers and excited state characteristics of silica glasses implanted with Gd ions were studied by time-resolved pulsed cathodoluminescence. It was found that in the process of ion implantation, two types of new emission centers associated with Gd ions as well as Si quantum dots are formed in glassy silica. The distributions of excited states over the lifetime were found for both new centers and Si quantum dots. The nature of dispersion of the emission decay time was discussed in terms of structural disorder in the matrix. Thermal annealing and an increase in the ion fluence lead to the stimulation of the formation of Gd-related new centers and Si quantum dots. The micromechanisms for the formation of new Gd-related centers and two types of Si quantum dots were proposed on the basis of two scenarios for the introduction of Gd ions into the SiO2 network: insertion of Gd into interstitial voids near oxygen-deficient centers and Gd  →  Si substitution with subsequent expulsion of Si atoms to the interstitial voids. New emission oxygen-deficient centers and quantum dots created by ion-beam technology in silica glasses are of interest for the development of new functional materials for photonics, and micro- and opto-electronics.