Optical Properties of Nb~+ Ions Implanted Sapphire before and after Annealing

摘要

Sapphire crystals with different orientations may cone from implantation of Nb~+ ions under different conditions and succedent annealing at reducing atmosphere. Optical analysis results show that the main optical absorption bands lay in the higher energy side of the spectra in the samples. The absorption curves were evaluated by Gaussian fitting based on the F-type centers, which were confirmed by luminescence measurements. The results of Gaussian fitting show that there were F center, F~+ center, F_2 center, F_2~+ center and F_2~(+2) center in the Nb~+ ions implanted sapphire. After annealing at different temperature, all types of color centers decreased, and the higher the annealing temperature, the more the defects decreased. Sub-micrometer particles were observed by the scanning electron microscopy.