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Degradation of AlGaN-based UV-C SQW LEDs analyzed by means of capacitance deep-level transient spectroscopy and numerical simulations

F. Piva1, M. Pilati1, M. Buffolo1, N. Roccato1, N. Susilo2, D. Hauer Vidal2, A. Muhin2, L. Sulmoni2, T. Wernicke2, M. Kneissl2,3, C. De Santi1, G. Meneghesso1, E. Zanoni1, and M. Meneghini1,4

Published in:

Appl. Phys. Lett., vol. 122, no. 18, pp. 181102, doi:10.1063/5.0144783 (2023).


The lifetime of deep-ultraviolet light-emitting diodes (LEDs) is still limited by a number of factors, which are mainly related to semiconductor defects, and still need to be clarified. This paper improves the understanding of UV LED degradation, by presenting an analysis based on combined deep-level transient spectroscopy (C-DLTS), electro-optical characterization, and simulations, carried out before and during a constant current stress test. The original results of this paper are (i) C-DLTS measurements allowed us to identify three traps, two associated with Mg-related defects, also detected in the unaged device, and one related to point defects that were generated by the ageing procedure. (ii) Based on these results and on TCAD simulations, we explain the variation in the forward I–V by the degradation of the p-contact, due to Mg passivation. (iii) On the other hand, optical degradation is ascribed to an increase in defectiveness of the active region and surrounding areas, which led to a decrease in injection efficiency, to an increase in non-radiative recombination, and to an increase in trap-assisted tunneling processes.

1 Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova, Italy
2 Technische Universität Berlin, Institute of Solid State Physics, Hardenberstr. 36, Berlin, Germany
3 Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
4 Department of Physics and Astronomy, University of Padova, via Marzolo 8, 35131 Padova, Italy


Crystallographic defects, Doping, Semiconductors, Light emitting diodes, Ultraviolet light, Deep level transient spectroscopy, Arrhenius plot

Published under an exclusive license by AIP Publishing. https://doi.org/10.1063/5.0149986
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