The formation of nanoparticles (NPs) in insulators via ion implantation has been widely studied due to the possibility to combine the versatility of ion implantation with the novel and interesting properties NPs. In particular, the intense UV and B-V photoluminescence (PL) of silica layers implanted with group-14 elements has been associated with the formation of point defects in the vitreous silica. These defects are usually referred to as oxygen deficient centers (ODCs)1. The ODC population and hence the emission properties depends upon the NP system structural evolution as controlled by the implantation temperature, annealing temperature and atmosphere.
In previous contributions we demonstrated that the classical NP nucleation and growth behaviour observed for high temperature treatments in Sn+ implanted silica can be avoided when samples previously submitted to a low temperature (250 ºC) and long time (100 h) ageing process2. It has been demonstrated recently that the ageing process leads to the formation of a distribution of small NPs that do not coarse even for high temperature thermal treatment with significant consequences to the B-V photoluminescence for this system3.
In this work report on a TEM and EXAFS study of Sn+ implanted SiO2 films. Post implantation ageing followed by high temperature thermal annealing in the 500 ≤ T ≤ 1100 ºC was then performed. Another set of (control) samples was submitted only to the high temperature treatment. After synthesis the samples where then characterized with a combination of RBS, PL, TEM and EXAFS.
For the non-aged control samples, the mean particle size increases as a function of temperature (metallic system). On the other hand the aged group shows the formation of a thermally stable and rather small distribution of NPs (oxidized system) which is correlated with the enhancement of the B-V PL.