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V-Pits-Induced Photoresponse Enhancement in AlGaN UV-B Photodetectors on Si (111)

Rathkanthiwar, S and Kalra, A and Muralidharan, R and Nath, DN and Raghavan, S (2020) V-Pits-Induced Photoresponse Enhancement in AlGaN UV-B Photodetectors on Si (111). In: IEEE Transactions on Electron Devices, 67 (10). pp. 4281-4287.

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Official URL: https://dx.doi.org/10.1109/TED.2020.3014852


We demonstrate the influence of surface terminated V-pits in tuning dark current and spectral responsivity of Al0.25Ga0.75N-based UV-B photodetectors with metal-semiconductor-metal geometry on Si (111) substrate. We show that the V-pit morphological defects contribute to a large internal gain in these photodetectors, thereby leading to a substantial enhancement in external quantum efficiency (EQE) at relatively low applied biases. For photodetectors fabricated on metal organic chemical vapor deposition grown Al0.25Ga0.75N epilayers with a surface pit density of 2 � 108 cm-2, an EQE of 100 was measured at a meager bias of 1.7 V, which increased significantly with bias. The EQE, photo-To-dark current ratio, and UV-To-visible rejection ratio measured 5 � 104, 1.2 � 104, and 2 � 103, respectively, at 5 V. The evidence of localized enhancement of photoresponse at the surface terminations of V-pits is exemplified by UV-Assisted conductive atomic forcemicroscopy. Temperature-dependent carrier transport analysis under dark and UV illumination revealed cumulative contributions of pit-induced thermionic field emission and hole-Trapping-induced gain to the observed large EQE. This work presents the highest value of responsivity for III-nitride UV-B detectors at a given bias. © 1963-2012 IEEE.

Item Type: Journal Article
Publication: IEEE Transactions on Electron Devices
Publisher: Institute of Electrical and Electronics Engineers Inc.
Additional Information: The copyright of this article belongs to Institute of Electrical and Electronics Engineers Inc.
Keywords: Aluminum gallium nitride; III-V semiconductors; Image enhancement; Metallorganic chemical vapor deposition; Organic chemicals; Organometallics; Photodetectors; Photons; Semiconducting aluminum compounds; Semiconductor alloys; Substrates; Wide band gap semiconductors, External quantum efficiency; Metal semiconductor metal; Morphological defects; Spectral responsivity; Surface pit densities; Surface termination; Temperature dependent; Thermionic field emission, Semiconducting gallium compounds
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 04 Dec 2020 10:32
Last Modified: 04 Dec 2020 10:32
URI: http://eprints.iisc.ac.in/id/eprint/67088

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