CUED Publications database

Broadband MoS<inf>2</inf> Field-Effect Phototransistors: Ultrasensitive Visible-Light Photoresponse and Negative Infrared Photoresponse

Wu, JY and Chun, YT and Li, S and Zhang, T and Wang, J and Shrestha, PK and Chu, D (2018) Broadband MoS<inf>2</inf> Field-Effect Phototransistors: Ultrasensitive Visible-Light Photoresponse and Negative Infrared Photoresponse. Advanced Materials, 30. ISSN 0935-9648

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Abstract

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Inverse photoresponse is discovered from phototransistors based on molybdenum disulfide (MoS2). The devices are capable of detecting photons with energy below the bandgap of MoS2. Under the illumination of near-infrared (NIR) light at 980 and 1550 nm, negative photoresponses with short response time (50 ms) are observed for the first time. Upon visible-light illumination, the phototransistors exhibit positive photoresponse with ultrahigh responsivity on the order of 104–105 A W−1 owing to the photogating effect and charge trapping mechanism. Besides, the phototransistors can detect a weak visible-light signal with effective optical power as low as 17 picowatts (pW). A thermally induced photoresponse mechanism, the bolometric effect, is proposed as the cause of the negative photocurrent in the NIR regime. The thermal energy of the NIR radiation is transferred to the MoS2 crystal lattice, inducing lattice heating and resistance increase. This model is experimentally confirmed by low-temperature electrical measurements. The bolometric coefficient calculated from the measured transport current change with temperature is −33 nA K−1. These findings offer a new approach to develop sub-bandgap photodetectors and other novel optoelectronic devices based on 2D layered materials.

Item Type: Article
Uncontrolled Keywords: bolometric effect inverse photoresponse molybdenum disulfide sub-bandgap photodetector ultrahigh photoresponsivity
Subjects: UNSPECIFIED
Divisions: Div B > Photonics
Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 03 Jan 2018 20:10
Last Modified: 25 Feb 2021 06:12
DOI: 10.1002/adma.201705880