Photoluminescence properties of in situ Tm-doped AlxGa1-xN

We report on the photoluminescence (PL) properties of in situ Tm-doped AlxGa1-xN films (0less than or equal toxless than or equal to1) grown by solid-source molecular-beam epitaxy. It was found that the blue PL properties of AlxGa1-xN:Tm greatly change as a function of Al content. Under above-gap pumping, GaN:Tm exhibited a weak blue emission at similar to478 nm from the (1)G(4)-->H-3(6) transition of Tm3+. Upon increasing Al content, an enhancement of the blue PL at 478 nm was observed. In addition, an intense blue PL line appeared at similar to465 nm, which is assigned to the D-1(2)-->F-3(4) transition of Tm3+. The overall blue PL intensity reached a maximum for x=0.62, with the 465 nm line dominating the visible PL spectrum. Under below-gap pumping, AlN:Tm also exhibited intense blue PL at 465 and 478 nm, as well as several other PL lines ranging from the ultraviolet to near-infrared. The Tm3+ PL from AlN:Tm was most likely excited through defect-related complexes in the AlN host. (C) 2003 American Institute of Physics.