Direct and indirect photoluminescence excitation and ultraviolet emission from Tm-doped AlxGa1-xN
We provide experimental evidence for direct and indirect excitations of photoluminescence (PL) from Tm-doped AlxGa1-xN of varying Al content. Direct excitation of Tm3+ ions is observed primarily at 85 K through transitions 3H6 → 1I 6, 3P0, 3P1, and 3P2 when these levels are below the absorption edge of the AlxGa1-xN for a given Al content. Strong ultraviolet emission at 298 nm (1I6 → 3H6), 355 nm (1I6 → 3F4), and 371 nm (1D2 → 3H6), as well as the familiar blue emission at 463 nm (1D2 → 3F4), and 479 nm (1G4 → 3H6), is found to depend sensitively on the Al content, excitation wavelength (i.e., direct or indirect), excitation type (continuous wave versus pulsed), and upper state of the transition. PL excitation spectroscopy and time-integrated and time-resolved PL spectra are compared to elucidate the complex energy transfer pathways. © 2009 American Institute of Physics.
Glinka, YD; Foreman, JV; Everitt, HO; Lee, DS; Steckl, AJ
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