Enhancement of luminescence by pulse laser annealing of ion-implanted europium in sapphire and silica

Abstract

Sapphire (Al2O3) and silica samples have been implanted with 400 keV europium ions at fluences between 5×1014 and 1×1016 ions cm−2. As-implanted, samples show luminescence at 622 nm, and although the intensity may be increased by furnace anneals up to 1000 °C, higher temperatures, to 1200 °C, result in less emission, as the impurity ions form precipitate clusters. This problem can be avoided by the use of pulsed laser anneals which dissociate the clusters and quench in atomically dispersed ions. The luminescence intensity has been increased by factors of 95 and 85 for sapphire and silica, respectively, relative to the initial implanted signal. On comparing with furnace anneals at 1200 °C, the pulsed laser annealing is more effective, by factors of up to 45 times. Data for pulsed excimer and CO2 lasers are compared. Both types of laser appear to remove the ion-implanted radiation damage, but in the case of silica, higher luminescence performance was obtained with the excimer anneals. There was no evidence for diffusion of the implanted europium, as assessed by Rutherford backscattering spectrometry.