Crystal-field splitting of Pr3+ (4f (2)) energy levels in GaN

We have calculated the crystal-field splitting of the energy levels of Pr3 in GaN and have compared these results to an analysis reported recently of the photoluminescence and the cathodoluminescence spectra of Pr3+ implante d in GaN by metal organic chemical vapor deposition on sapphire substrates. The lattice location of Pr in GaN determined recently by the emission chan neling technique, provides direct evidence that substitutional Ga sites are thermally stable lattice positions for Pr. The lattice-sum calculations wi th Pr occupying Ga sites include effective ionic charges, multipole polariz abilities, and structural information also available in the literature. Fro m the calculations, we conclude that the majority of the reported emission spectra is associated with Pr3+ ions in a common site with transitions from excited P-3(0) and P-3(1) states to crystal-field split multiplets, H-3(4) (the ground state), F-3(J), and (1)G(4). (C) 2001 American Institute of Ph ysics.