AlGaN Metal-Semiconductor-Metal Photodetectors on Planar and Epitaxial Laterally Overgrown AlN/Sapphire Templates for the Ultraviolet C Spectral Region

A. Knigge, M. Brendel, F. Brunner, S. Einfeldt, A. Knauer, V. Kueller, U. Zeimer, M. Weyers

Published in:

Jpn. J. Appl. Phys., vol. 52, no. 08JF03 (2013).

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Abstract:

Schottky type metal-semiconductor-metal (MSM) Al0.4Ga0.6N photodetectors (PDs) for the ultraviolet C spectral region on conventional planar AlN templates are compared with epitaxial laterally overgrown (ELO) AlN templates. On planar templates solar blind MSM PDs with state-of-theart dark current in the pA range and a power independent responsivity are obtained. PDs on ELO templates with fingers parallel to the etched stripes have properties similar to those on planar templates. PDs on ELO templates with contact fingers oriented perpendicular to the etched stripe pattern exhibit photoconductive gain leading to external quantum efficiencies of up to 77 at 30 V applied bias surpassing that of the planar grown PDs by a factor of 100. In spite of the high gain these PDs also show low dark currents, short switching times and two operating regimes with power independent responsivity.

Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany