Impact of open-core threading dislocations on the performance of AlGaN metal-semiconductor-metal photodetectors

S. Walde, M. Brendel, U. Zeimer, F. Brunner, S. Hagedorn, and M. Weyers

Published in:

J. Appl. Phys., vol. 123, no. 16, pp. 161551 (2018).

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The influence of open-core threading dislocations on the bias-dependent external quantum efficiency (EQE) of bottom-illuminated Al0.5Ga0.5N/AlN metal-semiconductor-metal (MSM) photodetectors (PDs) is presented. These defects originate at the Al0.5Ga0.5N/AlN interface and terminate on the Al0.5Ga0.5N surface as hexagonal prisms. They work as electrically active paths bypassing the Al0.5Ga0.5N absorber layer and therefore alter the behavior of the MSM PDs under bias voltage. This effect is included in the model of carrier collection in the MSM PDs showing a good agreement with the experimental data. While such dislocations usually limit the device performance, the MSM PDs benefit by high EQE at a reduced bias voltage while maintaining a low dark current.

Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany