EFFECT OF GROWTH TEMPERATURE AND DOPING CONCENTRATION ON THE DISTRIBUTION OF THE EMITTING CENTERS IN CAF2-ER MOLECULAR-BEAM EPITAXIAL LAYERS

Molecular beam epitaxy of Er-doped CaF2 layers on (100)oriented CaF2 s ubstrates was performed using CaF2 and ErF3 evaporation cells. The eff ect of growth temperature and Er concentration on the distribution of the different emission centers observed in these epitaxial Er-doped la yers was investigated. Photoluminescence analyses were performed in th e 830-860 nm wavelength range in which the S-4(3/2)-->I-4(3/2) transit ions of the Er3+ ions take place. The evolution of the relative emissi on intensity between single and aggregate Er3+ centers as a function o f growth temperature shows that the emission from isolated Er3+ ions i s favored in a growth temperature range of 500-520-degrees-C. Emission lines from complex Er3+ centers are found to rise relative to those o f isolated sites as Er concentration increases. Finally, no quenching of the integrated luminescence intensity occurs in the concentration r ange investigated, 0.05-6 mol % (0.1-1 6 wt%).