Abstract
This paper investigates the factors that influence the efficiency and the reliability of InGaN-based light emitting diodes. The devices under test have a single InGaN quantum well, with a nominal emission wavelength of 495 nm. From the preliminary characterization, the L-I curve shows an anomalous slope mainly due to: i) high Shockley Read Hall recombination rate, and ii) low electron densities in the explored range of injection, as also confirmed by simulation. The reliability of the devices was investigated by performing a constant current stress test at J = 80 A/cm2 at room temperature. Optical degradation occurs with different trends, depending on the injection regime. For low injection levels, the optical power decay is monotonic. In the high injection range, for I > 10 mA, we can recognize different degradation phases. The optical degradation can be ascribed to the generation and relocation of defects in the active region, as also confirmed by DLOS measurement. The origin of degradation was also investigated by a stress test with photoluminescence measurement. The results suggest that the variation of the optical characteristics can be related to the variation of the intrinsic characteristics of the material.
Published Version
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