Interdigitated electrode geometry variation and external quantum efficiency of GaN/AlGaN-based metal-semiconductor-metal UV photodetectors

S. F. Nwabunwanne; W. R. Donaldson

doi:10.1117/12.2608355

5 March 2022 Interdigitated electrode geometry variation and external quantum efficiency of GaN/AlGaN-based metal-semiconductor-metal UV photodetectors

S. F. Nwabunwanne, W. R. Donaldson

Author Affiliations +

Proceedings Volume 12001, Gallium Nitride Materials and Devices XVII; 120010F (2022) https://doi.org/10.1117/12.2608355
Event: SPIE OPTO, 2022, San Francisco, California, United States

Conference Poster

Abstract

Aluminum gallium-nitride (Al_xGa_1–xN)-based metal−semiconductor−metal (MSM) ultraviolet photodetectors photodetectors (PD’s) have been successfully designed and fabricated using conventional photolithography techniques and tested experimentally to study their spectral sensitivity across different Al content, x, with x varying from 0 to 0.3. (Al)GaN-based UV PD’s have wide and tunable direct band gaps. The ability to easily select the photodetected wavelength by simply varying the aluminum content of GaN thin film (Al_xGa_1–xN) is a significant advantage of these group III–V compounds. Typically, MSM PD’s grown on (Al)GaN thin films result in ultrafast photodetection because of their highly mobile carriers. These devices are limited by the carrier transit time due to the negligible capacitance presented by the interdigitated fingers. Various electrode geometries were fabricated to investigate the influence of metal contact shapes on the devices’ performance indices with emphasis on the response speed and bias-voltage–independent efficiency. Coupled with the independently measured Hall mobility and electric field, we computed the carrier transit time of the devices to be as short as 1.31 ps and the bias-voltage−independent external quantum efficiencies were as high as 70% at 60 V for n-doped and intrinsic devices when operated in the reverse bias regime. Here, (Al_x)Ga_1–xN photodetectors were designed to explore spectral sensitivity by altering x from 0 to 0.3.

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S. F. Nwabunwanne and W. R. Donaldson "Interdigitated electrode geometry variation and external quantum efficiency of GaN/AlGaN-based metal-semiconductor-metal UV photodetectors", Proc. SPIE 12001, Gallium Nitride Materials and Devices XVII, 120010F (5 March 2022); https://doi.org/10.1117/12.2608355

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