title: Single Defect Light-Emitting Diode in a van der Waals Heterostructure.
abstract: Single defects in monolayer WSe2 have been shown to be a new class of single photon emitters and have potential applications in quantum technologies. Whereas previous work relied on optical excitation of single defects in isolated WSe2 monolayers, in this work we demonstrate electrically driven single defect light emission by using both vertical and lateral van der Waals heterostructure devices. In both device geometries, we use few layer graphene as the source and drain and hexagonal boron nitride as the dielectric spacer layers for engineered tunneling contacts. In addition, the lateral devices utilize a split back gate design to realize an electrostatically defined p-i-n junction. At low current densities and low temperatures (∼5 K), we observe narrow spectral lines in the electroluminescence (EL) whose properties are consistent with optically excited defect bound excitons. We show that the emission originates from spatially localized regions of the sample, and the EL spectrum from single defects has a doublet with the characteristic exchange splitting and linearly polarized selection rules. All are consistent with previously reported single photon-emitters in optical measurements. Our results pave the way for on-chip and electrically driven single photon sources in two-dimensional semiconductors for quantum technology applications.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Clark
authors.forename: John R
authors.initials: JR
authors.lastname: Schaibley
authors.forename: Jason
authors.initials: J
authors.lastname: Ross
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Air Force Research Laboratory, Sensors Directorate , Wright-Patterson AFB, Ohio 45433, United States.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Hendrickson
authors.affiliation: Air Force Research Laboratory, Materials & Manufacturing Directorate , Wright-Patterson AFB, Ohio 45433, United States.
authors.forename: Shin
authors.initials: S
authors.lastname: Mou
authors.affiliation: Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong , Hong Kong, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Yao
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
keywords: Transition metal dichalcogenides; electroluminescence; single defect; tungsten diselenide; van der Waals heterostructure