Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes

A pulse-driven emission-spectroscopy mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode, and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emi...

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Veröffentlicht in:Applied physics letters 2015-08, Vol.107 (8)
Hauptverfasser: Ishii, Masashi, Koizumi, Atsushi, Fujiwara, Yasufumi
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Sprache:eng
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Zusammenfassung:A pulse-driven emission-spectroscopy mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode, and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emission spectral data yields a three-dimensional mapping that allows the origin of emission lines to be identified by visual inspection. The identification was achieved even for a weak 5D0 → 7F3 transition in conventional photoluminescence measurements. A peculiar split is observed in the 5D0 → 7F3 transition for the bright emission center referred to as OMVPE 8. Despite the unique transition at this emission center, the emission efficiencies for the 5D0 → 7F3 and 5D0 → 7F2 transitions were identical. This finding indicates that the excitation of the emission centers, rather than the radiative transitions, is the limiting process that determines the GaN:Eu red LED brightness.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4929531