Gate-Switchable Arrays of Quantum Light Emitters in Contacted Monolayer MoS₂ van der Waals Heterodevices

Abstract

We demonstrate electrostatic switching of individual, site-selectively generated matrices of single photon emitters (SPEs) in MoS2 van der Waals heterodevices. We contact monolayers of MoS2 in field-effect devices with graphene gates and hexagonal boron nitride as the dielectric and graphite as bottom gates. After the assembly of such gate-tunable heterodevices, we demonstrate how arrays of defects, that serve as quantum emitters, can be site-selectively generated in the monolayer MoS2 by focused helium ion irradiation. The SPEs are sensitive to the charge carrier concentration in the MoS2 and switch on and off similar to the neutral exciton in MoS2 for moderate electron doping. The demonstrated scheme is a first step for producing scalable, gate-addressable, and gate-switchable arrays of quantum light emitters in MoS2 heterostacks.

The role of chalcogen vacancies for atomic defect emission in MoS2

“…The small exciton redshift in the He-ion treated sample can likely be attributed to the increased dielectric screening in the fully encapsulated samples 28 . Additionally, inhomogeneous broadening effects due to a locally varying dielectric environment near the defects may result in an uncertainty of the defect emission line on the order of several meV 29,30 . The improved inhomogeneous broadening agrees with previous studies of fully hBN encapsulated heterostructures 26 .…”

“…These experiments are conducted on graphene/SiC heterostructures. The graphene substrate is essential as conductive support, but it quenches the defect emission, which is slow (100 ns-1 μs) 3,29,30 , and therefore the fast exciton emission (~10 ps) dominates on graphene (Supplementary Note 5) 16,39 . For STM, all samples were prepared in-vacuo by a mild annealing step in vacuum (T annealing < 500 K) to remove adsorbates.…”

Prospects and challenges of quantum emitters in 2D materials

“…TMDs are amongst the few hosts for quantum emitters that can benefit from the electrical injection of SPEs forming a quantum light-emitting diode (LED) 56,57 . Moreover, electrostatic gating of emitters in TMDs has been useful in externally controlling their emission characteristics 15,21 .…”

“…Emitters in atomically thin host materials can be more easily accessed and interfaced to judiciously designed electronic and photonic devices to facilitate their integration. Moreover, as recent experiments have shown, emitters in 2D materials are well-suited for realizing deterministic arrays of SPEs that can be externally addressed with electrically controllable switching of emission from the SPEs 21 .…”

Gate‐Tunable Magnetism via Resonant Se‐Vacancy Levels in WSe2

“…[ 11 , 12 , 13 ] In particular, the confined defects in 2D semiconductors offer an opportunity for tailoring the electronic and magnetic properties using external forces such as strain, gate bias, electric fields, or ambient environment. [ 3 , 5 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ] In vdW‐layered transition metal dichalcogenides (TMDs), intrinsic defects such as transition metals and chalcogen vacancies are often observed. [ 22 , 23 , 24 ] Transition metal vacancies generate magnetic properties; [ 25 , 26 , 27 ] for example, the long‐range magnetic order in PtSe 2 is induced by the Pt vacancies inherited from the formation of occupied mid‐gap states.…”