With this paper we present an extensive analysis of localized emission process that occur at low current densities in InGaN/GaN LEDs. The study was carried out by means of spatially resolved EL measurements performed at different temperatures and currents. Results indicate that, (i) when green LEDs are biased at low current densities, localized yellow-emitting spots can be identified; (ii) the presence of yellow-emitting dots is strongly correlated to the existence of strong tunneling components in the I-V curves; (iii) yellow-emitting dots (YEDs) can be detected by EL measurements, and not by PL investigation; (iv) localized yellow luminescence is strongly thermally-activated, with activation energy equal to 0.64 eV. The presence of YEDs is ascribed to defect-related recombination of electrons that tunnel to the barrier layers.
Electrical, spectral and thermal analysis of yellow luminescent dots in InGaN green LEDs
TRIVELLIN, NICOLA;MENEGHINI, MATTEO;VACCARI, SIMONE;MENEGHESSO, GAUDENZIO;ZANONI, ENRICO
2012
Abstract
With this paper we present an extensive analysis of localized emission process that occur at low current densities in InGaN/GaN LEDs. The study was carried out by means of spatially resolved EL measurements performed at different temperatures and currents. Results indicate that, (i) when green LEDs are biased at low current densities, localized yellow-emitting spots can be identified; (ii) the presence of yellow-emitting dots is strongly correlated to the existence of strong tunneling components in the I-V curves; (iii) yellow-emitting dots (YEDs) can be detected by EL measurements, and not by PL investigation; (iv) localized yellow luminescence is strongly thermally-activated, with activation energy equal to 0.64 eV. The presence of YEDs is ascribed to defect-related recombination of electrons that tunnel to the barrier layers.
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