John B. Gruber
University of Texas at San Antonio
"Optical Properties of Rare-Earth Doped
Wide Band Gap Semiconductors"
Wide band gap semiconductors implanted with rare earth ions have unique luminescence properties that make them useful in a great variety of photonic applications. In turn, the rare earth ions themselves act as probes in the study concerning local impurity environments and defects, some of which are related to energy transfer and carrier scattering in the lattice. In this presentation we describe the luminescence properties, lattice locations, and the crystal-field splitting of the energy levels of trivalent Pm, Sm, Gd, and Tm in 2H-AlN. The rare earth ion size contraction across the series is evident in terms of changes in the local environments in the AlN lattice. This is also the case when these ions are implanted in GaN, but to a lesser extent. The nature of the impurity traps that are formed appear to affect the quantum efficiencies of the ions beyond Gd in the rare earth series and may account for a threshold excitation energy around 4 eV observed in the 465 and 478 nm f to f transitions in Tm 3+ in AlN.
Tuesday
May 16, 2006
4:10 p.m. -- Stocker 103