Optical and structural studies in Eu-implanted AlN films

Eu ions were incorporated into AlN thin films using ion implantation, and the influence of the post-implant annealing ambient on structural and optical properties was investigated. Eu is incorporated into lattice sites which are slightly displaced from the substitutional Al sites. When compared with the as-implanted sample the near-substitutional ion fraction is reduced due to the thermal annealing in different atmospheres. The AlN crystal quality does not change with different annealing conditions, but sensitive defect-related emission bands are developed under different annealing temperatures. Eu3+ optical activation is detected for all the annealed samples. No spectral changes are observed for the shape of the intra-4f6D05→F27 transition, suggesting that a similar site symmetry is preserved even when a slight displacement from the substitutitional site of the Eu3+ ions occurs. The role of the annealing conditions on the spectral position and thermal quenching of the D05→F27 transition is discussed.