Asymmetric photoelectric effect: Auger-assisted hot hole photocurrents in transition metal dichalcogenides
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 25, 2020
- Source ID
- 10.1515/nanoph-2020-0397
Entities
People
- Alexander Efros
- Andrew Y Joe
- Andrey Sushko
- Bernhard Urbaszek
- C Stephen Hellberg
- Hongkun Park
- Kenji Watanabe
- Kristiaan De Greve
- Madeleine Phillips
- Mikhail Lukin
- Philip Kim
- Takashi Taniguchi
Organizations
- Air Force Office of Scientific Research
- Core Research for Evolutional Science and Technology
- Harvard University
- Interuniversity Microelectronics Centre
- Japan Society for the Promotion of Science
- Ministry of Education, Culture, Sports, Science and Technology
- National Institute for Materials Science
- National Science Foundation
- United States Naval Research Laboratory
- University of Toulouse (1896-1968)