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We report Fe 3ϩ -related emission in ion-implanted ZnO single crystals. Iron ions were implanted at room temperature with 100 keV and a fluence of 1ϫ10 16 Fe ϩ /cm 2 , and were submitted to annealing treatments in vacuum and in air. After implantation, the damage raises the minimum yield ( min ) from 2% to 50%. Annealing in an oxidizing atmosphere leads to a reduction of the implantation damage, which is fully recovered after annealing at 1050°C with a min ϳ3% in the implanted region. With extrinsic excitation, red Fe-related emission is observed at low temperatures. The intensity is dependent on the annealing conditions. For samples annealed in air, the luminescence can be detected up to 120 K. When a comparison is made between unimplanted and post-implanted annealed samples, noticeable changes on near-band-edge and deep-level photoluminescence spectra are observed. A thermally populated structured green emission could be observed in the sample annealed in air, as shown by the temperature-dependent photoluminescence excitation studies.

A series of rare earth elements (RE) were implanted in GaN epilayers to study the lattice site location and optical activity. Rutherford backscattering spectrometry in the channeling mode(RBS/C) was used to follow the damage behavior in the Ga sublattice and the site location of the RE. For all the implanted elements (Ce, Pr, Dy, Er, and Lu) the results indicate the complete substitutionality on Ga sites after rapid thermal annealing at 1000 o C for 2 min. The only exception occurs for Eu that occupies a Ga displaced site. Annealing at 1200 o C in nitrogen atmosphere at a pressure of 1GPa is necessary to achieve the complete recovery of the damage in the samples. After annealing the recombination processes of the implanted samples were studied by above and below band gap excitation. For Er implanted samples besides the 1.54 m emission green and red emissions are also observed. Red emissions from 5 D0 7 F2 and 3 P0 3 F2 transitions were found in Eu and Pr implanted samples even at room temperature.