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Thermally-activated degradation of InGaN-based laser diodes: Effect on threshold current and forward voltage

: Santi, C. de; Meneghini, M.; Marioli, M.; Buffolo, M.; Trivellin, N.; Weig, T.; Holc, K.; Köhler, K.; Wagner, J.; Schwarz, U.T.; Meneghesso, G.; Zanoni, E.


Microelectronics reliability 54 (2014), No.9-10, pp.2147-2150
ISSN: 0026-2714
European Symposium on the Reliability of Electron Devices, Failure Physics and Analysis (ESREF) <25, 2014, Berlin>
Journal Article, Conference Paper
Fraunhofer IAF ()
GaN; laser diode; reliability; threshold current; constant bias stress; thermal storage

This paper presents a study of the effects of high temperature stress on the electro-optical characteristics of violet InGaN-based laser diodes. The results indicate that: (i) when submitted to constant current stress (with relatively high junction temperatures), devices show a significant increase in threshold current (I(th)), related to the increase in non-radiative recombination; micro-cathodoluminescence measurements indicate that the area affected by degradation is wider than the ridge; (ii) the results of purely-thermal stress test indicate that the exposure to high temperature may induce an increase in threshold current; (iii) during the first part of the stress, this mechanism is well correlated with the variation of the forward voltage, suggesting a degradation in the properties (conductivity, acceptor doping) of the p-type material; for longer stress times, a further Ith increase is detected, with a linear dependence on time.