Single-crystal sapphire (α- Al2O3) was implanted at room temperature with 200 keV erbium ions to a fluence of 8 X 1013 cm-2. Ion channeling using 1.6 MeV He+ shows that the crystal suffers little damage for this low dose implant. Angular scans through axial and planar directions in the crystal indicate that 70% of the Er atoms reside on displaced octahedral sites in the α- Al2O3 lattice. As pure l2O3 has a high density of free octahedral sites, this explains why high concentrations of Er can be dissolved in this material. Smaller fractions of Er are found on tetrahedral (20%) and random (10%) sites. The samples exhibit strongly peaked photoluminescence spectra around 1.5 µm, due to intra-4f transitions in Er3+, indicating the existence of well defined sites for the luminescing Er3+ ions. It is concluded that the octahedral site is the dominating optically active site in the lattice.

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Journal J. Mater. Res.
Citation
van den Hoven, G.N, Polman, A, Alves, E, da Silva, M.F, Melo, A.A, & Soares, J.C. (1997). Lattice site and photoluminescence of erbium implanted in a - Al2O3. J. Mater. Res., 12, 1401–1404.