Thermal quenching of luminescence and isovalent trap model for rare‐earth‐ion‐doped AlN

Abstract

Investigations of the luminescent properties of Pr-, Eu-, Tb-and Tm-implanted AlN thin films at temperature in the range 9 -830 K are reported. The temperature studies of photoluminescence and cathodoluminescence spectra revealed unexpectedly weak thermal quenching for all investigated rare earth (RE) ions. The maximum CL emission is observed from Eu (red) at 485 K, Tb (green) at 590 K and Tm (blue) at 530 K, respectively. For Tb-and Tm-doped AlN samples, temperature-dependent crossrelaxation processes were observed. Photoluminescence excitation spectra, obtained under UV excitation in the spectral range 200 -400 nm, exhibit several bands. It is proposed that the RE ions exist in semiconductors as isolated ions (singlet), nearest-neighbor (nn) ion pairs (dimer), and three ions (trimer). The Koster -Slater and simple spherical potential-well models for RE-structured isovalent (RESI) hole trap are proposed. The exciton binding energies of RESI traps are calculated and compared with experimental thermal-quenching energies. The energy-transfer processes between the AlN host and the 4f-shell systems are emphasized as the main mechanisms for thermal-quenching processes rather than nonradiative decay of 4f transitions.

Atomic Structure of Luminescent Centers in High-Efficiency Ce-doped w-AlN Single Crystal

“…The present rare-earth doping process in w -AlN is thus highly effective, and all Ce dopants should contribute equally to the pink-colored luminescence. Note that, even after the extensive observations, we could not observe any rare-earth dimer- or trimer-clusters, as previously proposed1214, suggesting that these clusters may be meta-stable defect structures. In the high-magnification atomic-resolution ADF STEM image of Figure 2(b), the single Ce dopant evidently substitutes for the Al site without apparent atomic displacements.…”

Luminescence of Eu ions inAlxGa1−xNacross the entire alloy composition range

“…10 Additionally the presence of the X 2 excitation band must still be explained. Lozykowski and Jadwisienczak 26 have argued that clustering of RE ions is responsible for a series of PLE features, which would correspond to a series of excitation features X 1,2,. . .,n ; however such clustering would lead to characteristic features in the emission spectra of some RE ions 27 and we still have the problem of excitation transfer from cluster to single ion to contend with.…”

Параметры пленок ZnO с дырочным типом проводимости, полученных методом высокочастотного магнетронного распыления

“…В настоящее время исследованиям пленок ZnO пря-мозонного широкозонного полупроводника, перспектив-ного материала для создания различных приборов на его основе, посвящен целый ряд работ [1][2][3][4][5][6].…”