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Title: Evidence of minority carrier injection efficiency >90% in an epitaxial graphene/SiC Schottky emitter bipolar junction phototransistor for ultraviolet detection

In this letter, we report the UV detection characteristics of an epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistor (SEPT) with EG on top as the transparent Schottky emitter layer. Under 0.43 μW UV illumination, the device showed a maximum common emitter current gain of 113, when operated in the Schottky emitter mode. We argue that avalanche gain and photoconductive gain can be excluded, indicating minority carrier injection efficiency, γ, as high as 99% at the EG/p-SiC Schottky junction. This high γ is attributed to the large, highly asymmetric barrier, which EG forms with the p-SiC. The maximum responsivity of the UV phototransistor is estimated to be 7.1 A/W. The observed decrease in gain with increase in UV power is attributed to recombination in the base region, which reduces the minority carrier lifetime.
Authors:
; ; ; ; ; ;  [1]
  1. Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States)
Publication Date:
OSTI Identifier:
22489375
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 4; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARRIER LIFETIME; CARRIERS; EFFICIENCY; EPITAXY; GAIN; GRAPHENE; SEMICONDUCTOR JUNCTIONS; SILICON CARBIDES; ULTRAVIOLET RADIATION