We studied energy transfer from AlN to doped Gd 3þ ions as a function of the post-thermal annealing temperature. Gd-doped AlN thin films were deposited on fused-silica substrates using a reactive radio-frequency magnetron sputtering technique. The film is a c-axis oriented polycrystal. The intraorbital electron transition in Gd 3þ showed an atomically sharp luminescence at 3.9 eV (318 nm). The photoluminescence (PL) excitation spectrum exhibited a resonant peak, indicating efficient energy transfer from the host AlN crystal to Gd 3þ ions. The PL intensity increases approximately ten times by thermal annealing. The PL decay lifetime becomes long with annealing, and mid-gap luminescence relating to the crystal defects in AlN was also found to be reduced by annealing. These results suggest that energy dissipation of excited carriers in AlN was suppressed by annealing, and the efficiency of energy transfer into Gd 3þ was improved. V C 2015 AIP Publishing LLC.

Optoelectronic and structural characteristics of Er-doped amorphous AlN films J. Appl. Phys. 98, 093514 (2005); 10.1063/1.2127120Effect of growth temperature on morphology, structure and luminescence of Eu-doped GaN thin filmsWe studied the efficient indirect excitation of Gd 3þ ions in AlN thin films. C-axis oriented polycrystalline thin films of Al 0.997 Gd 0.003 N/AlN were grown on fused silica substrates using a reactive radio-frequency magnetron sputtering technique. The intra-orbital electron transition in Gd 3þ showed a narrow luminescence line at 3.9 eV. The photoluminescence (PL) excitation (PLE) spectrum exhibited a peak originating from efficient indirect energy transfer from the band edge of AlN to Gd 3þ ions. The PLE peak shifted and the PL intensity showed a dramatic change when the AlN band gap was varied by changing the temperature. Energy scanning performed by changing the band-gap energy of AlN with temperature revealed several resonant channels of energy transfer into the higher excited states of Gd 3þ . V C 2014 AIP Publishing LLC. [http://dx.