Localization of current-induced degradation effects in (InAlGa)N-based UV-B LEDs
J. Ruschel1, J. Glaab1, M. Brendel1, J. Rass1, C. Stölmacker1, N. Lobo-Ploch1, T. Kolbe1, T. Wernicke2, F. Mehnke2, J. Enslin2, S. Einfeldt1, M. Weyers1, and M. Kneissl1,2
Published in:
J. Appl. Phys., vol. 124, no. 8, pp. 084504 (2018).
Abstract:
The degradation behavior of ultraviolet-B light emitting diodes (UV-B LEDs) emitting near 310 nm has been investigated and a method to localize the degradation effects is presented. Measurements of the electro-optical characteristics of UV-B LEDs, during a 200 h constant-current degradation study, showed an initial fast decrease in the optical power accompanied by a decrease in the drive voltage and an increase in the capacitance. Furthermore, by using a specially designed contact geometry, it was possible to separate the degradation of the electrical properties of the p- layers and p-contacts from the degradation of the active region and n-side of the LED heterostructure. Our investigations show that the initial changes in capacitance and voltage can be attributed to changes in the p-side and at the p-contact of the LED, which can be explained by an activation of Mg dopants.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany
2 Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin, Germany
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