Luminescence of Eu ions in AlxGa1-xN across the entire alloy composition range

Wang, K. and O'Donnell, K.P. and Hourahine, B. and Martin, R.W. and Watson, I.M. and Lorenz, K. and Alves, E. (2009) Luminescence of Eu ions in AlxGa1-xN across the entire alloy composition range. Physical Review B, 80 (12). 125206. ISSN 1098-0121 (https://doi.org/10.1103/PhysRevB.80.125206)

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Abstract

Photoluminescence (PL) and PL excitation (PLE) spectra of Eu-implanted AlxGa1-xN are obtained across the whole alloy composition range. The dominant D-5(0)-F-7(2) emission band broadens and then narrows as x increases from 0 to 1 while the peak shifts monotonically. This behavior is surprisingly similar to the broadening of excitons in a semiconductor alloy caused by composition fluctuations [E. F. Schubert et al., Phys. Rev. B 30, 813 (1984). PLE spectra reveal a steplike AlxGa1-xN band-edge absorption and two "subgap" bands X-1,X-2:X-1 peaks at 3.26 eV in GaN and shifts linearly to 3.54 eV in AlN. For x > 0.6, X-2 emerges approximately 1 eV higher in energy than X-1 and shifts in a similar way. We propose that X-1,X-2 involve creation of core-excitonic complexes of Eu emitting centers.