title: Electric-field-induced strong enhancement of electroluminescence in multilayer molybdenum disulfide.
abstract: The layered transition metal dichalcogenides have attracted considerable interest for their unique electronic and optical properties. While the monolayer MoS2 exhibits a direct bandgap, the multilayer MoS2 is an indirect bandgap semiconductor and generally optically inactive. Here we report electric-field-induced strong electroluminescence in multilayer MoS2. We show that GaN-Al2O3-MoS2 and GaN-Al2O3-MoS2-Al2O3-graphene vertical heterojunctions can be created with excellent rectification behaviour. Electroluminescence studies demonstrate prominent direct bandgap excitonic emission in multilayer MoS2 over the entire vertical junction area. Importantly, the electroluminescence efficiency observed in multilayer MoS2 is comparable to or higher than that in monolayers. This strong electroluminescence can be attributed to electric-field-induced carrier redistribution from the lowest energy points (indirect bandgap) to higher energy points (direct bandgap) in k-space. The electric-field-induced electroluminescence is general for other layered materials including WSe2 and can open up a new pathway towards transition metal dichalcogenide-based optoelectronic devices.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
authors.forename: Dehui
authors.identifier: 000000025945220X
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Cheng
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
authors.forename: Hailong
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
authors.forename: Anxiang
authors.initials: A
authors.lastname: Yin
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Yu
authors.identifier: 0000000179997808
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Nathan O
authors.initials: NO
authors.lastname: Weiss
authors.affiliation: 1] Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA [2] California Nanosystems Institute, University of California, Los Angeles, California 90095, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.affiliation: 1] Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA [2] California Nanosystems Institute, University of California, Los Angeles, California 90095, USA.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Duan