Carrier density modulation and photocarrier transportation of graphene/InSb heterojunction middle-wavelength infrared photodetectors

Abstract

The photoresponse mechanism of graphene/InSb heterojunction middle-wavelength infrared (MWIR) photodetectors was investigated. The devices comprised a graphene/InSb heterojunction as a carrier-injection region and an insulator region of graphene on tetraethyl orthosilicate (TEOS) for photogating. The MWIR photoresponse was significantly amplified with an increase in the graphene/TEOS cross-sectional area by covering the entire detector with graphene. The graphene-channel dependence of the MWIR photoresponse indicated that the graphene carrier density was modulated by photocarrier accumulation at the TEOS/InSb boundary, resulting in photogating. The dark current of the devices was suppressed by a decrease in the graphene/InSb carrier-injection region and the formation of the heterojunction using an n-type InSb substrate. The results indicate that photocarrier transportation was dominated by the formation of a Schottky barrier at the interface of the graphene/InSb heterojunction and a Fermi-level shift under bias application. The high-responsivity and low-dark-current photoresponse mechanism was attributed to the graphene/InSb heterojunction diode behavior and the photogating effect. The devices combining the aforementioned features had a noise equivalent power of 0.43 pW∕Hz 1∕2. The results obtained in our study will contribute to the development of high-performance graphene-based IR image sensors. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

High-performance graphene mid-infrared photogated diode with interfacial layer for infrared image sensor

“…3,4 Consequently, these photodetectors have been extensively researched, with particular emphasis on improving the response by incorporating different electrode materials, 5 p-n junctions, 6,7 bolometers, 8 thermopiles, 9 plasmonic resonance, [10][11][12] graphene double-layer heterostructures, 13 van der Waals heterostructures, 14 and photogating. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] Most previously reported photodetectors had a field-effect transistor structure and exhibited ultra-high responsivity. However, as graphene has no bandgap, 29 these devices did not operate in the normally-off mode and had high dark current.…”

Graphene-based fabrication to boost performance of InAs/GaInSb type II superlattice infrared photodetectors

“…Among these, the photogating is the most promising technique in terms of improving the photodetectors performance, which cannot be achieved using conventional methods used to increase absorption efficiency. We demonstrated high performance InSb-based IR photodetectors using photogating in the MWIR region with graphene field effect transistors (GFET) [51,52] and graphene-InSb Schottky diode [53][54][55][56][57][58][59] structures. We labeled the former structure as graphene photogated FET (GPFET) and the latter as graphene photogated diode (GPD).…”

Graphene-based fabrication to boost performance of InAs/GaInSb type II superlattice infrared photodetectors

“…Among these, the photogating is the most promising technique in terms of improving the photodetectors performance, which cannot be achieved using conventional methods used to increase absorption efficiency. We demonstrated high performance InSb-based IR photodetectors using photogating in the MWIR region with graphene field effect transistors (GFET) [51,52] and graphene-InSb Schottky diode [53][54][55][56][57][58][59] structures. We labeled the former structure as graphene photogated FET (GPFET) and the latter as graphene photogated diode (GPD).…”