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Transition metal dichalcogenide (TMD) semiconductor heterostructures are actively explored as a new platform for quantum optoelectronic systems. Most state of the art devices make use of insulating hexagonal boron nitride (hBN) that acts as a wide-bandgap dielectric encapsulating layer that also provides an atomically smooth and clean interface that is paramount for proper device operation. We report the observation of large, through-hBN photocurrents that are generated upon optical excitation of hBN encapsulated MoSe2 and WSe2 monolayer devices. We attribute these effects to Auger recombination in the TMDs, in combination with an asymmetric band offset between the TMD and the hBN. We present experimental investigation of these effects and compare our observations with detailed, ab-initio modeling. Our observations have important implications for the design of optoelectronic devices based on encapsulated TMD devices. In systems where precise charge-state control is desired, the out-of-plane current path presents both a challenge and an opportunity for optical doping control. Since the current directly depends on Auger recombination, it can act as a local, direct probe of both the efficiency of the Auger process as well as its dependence on the local density of states in integrated devices.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Transition metal dichalcogenides, heterostructures, photocurrents

Date published: 2020-12-04

Publisher: Walter de Gruyter GmbH

Journal:

• Nanophotonics (ISSN: 21928614) vol. 10 issue. 1 p. 105-113

Funding:

• Japan Society for the Promotion of Science London JP20H00354
• DoD Vannevar Bush Faculty Fellowship N00014-15-1-2846N00014-16-1-2825N00014-18-1-2877
• National Science Foundation PHY-1506284
• DoD High Performance Computing Modernization Program NRLDC04123333
• Ministry of Education, Culture, Sports, Science and Technology JPMXP0112101001
• Core Research for Evolutional Science and Technology JPMJCR15F3
• Air Force Office of Scientific Research FA9550-17-1-0002

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1515/nanoph-2020-0397

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Updated at: 2025-02-26 12:31:17 +0900

Published on MDR: 2025-02-26 12:31:17 +0900