The photoluminescence/excitation (PL/E) spectroscopy of Eu-implanted GaN
✍ Scribed by K.P. O’Donnell; I.S. Roqan; Ke Wang; K. Lorenz; E. Alves; M. Boćkowski
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 301 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0925-3467
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✦ Synopsis
Several distinct luminescent centres form in GaN samples doped with Eu. One centre, Eu2, recently identified as the isolated, substitutional Eu impurity, Eu Ga , is dominant in ion-implanted samples annealed under very high pressures (1 GPa) of N 2 . According to structural determinations, such samples exhibit an essentially complete removal of lattice damage caused by the implantation process. A second centre, Eu1, probably comprising Eu Ga in association with an intrinsic lattice defect, produces a more complex emission spectrum. In addition there are several unidentified features in the 5 D 0 to 7 F 2 spectral region near 620 nm. We can readily distinguish Eu1 and Eu2 by their excitation spectra, in particular through their different sensitivities to above-gap and below-gap excitation. The present study extends recent work on photoluminescence/excitation (PL/E) spectroscopy of Eu1 and Eu2 to arrive at an understanding of these mechanisms in terms of residual optically active defect concentrations. We also report further on the 'host-independent' excitation mechanism that is active in the case of a prominent minority centre. The relevance of this work to the operation of the red GaN:Eu light-emitting diode is discussed.