High‐speed solar‐blind AlGaN‐based metal–semiconductor–metal photodetectors

Solar‐blind AlGaN metal–semiconductor–metal (MSM) photodetectors with fast pulse response have been demonstrated. The devices were fabricated on MOCVD‐grown epitaxial Al 0.38 Ga 0.62 N layers, using a microwave compatible fabrication process. The photodiode samples exhibited low leakage with dark current densities below 1 × 10 −6 A/cm 2 at 40 V reverse bias. Photoconductive gain‐assisted photoresponse was observed with a peak responsivity of 1.26 A/W at 264 nm. A visible rejection of ∼3 orders of magnitude at 350 nm was demonstrated. Temporal high‐speed measurements at 267 nm resulted in fast pulse responses with 3‐dB bandwidths as high as 5.4 GHz. This corresponds to a record high‐speed performance for solar‐blind detectors. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)