Robust valley polarization of helium ion modified atomically thin MoS${}_2$

Abstract

Atomically thin semiconductors have dimensions that are commensurate with critical feature sizes of future optoelectronic devices defined using electron/ion beam lithography. Robustness of their emergent optical and valleytronic properties is essential for typical exposure doses used during fabrication. Here, we explore how focused helium ion bombardment affects the intrinsic vibrational, luminescence and valleytronic properties of atomically thin MoS${}_2$. By probing the disorder dependent vibrational response we deduce the interdefect distance by applying a phonon confinement model. We show that the increasing interdefect distance correlates with disorder-related luminescence arising 180 meV below the neutral exciton emission. We perform ab-initio density functional theory of a variety of defect related morphologies, which yield first indications on the origin of the observed additional luminescence. Remarkably, no significant reduction of free exciton valley polarization is observed until the interdefect distance approaches a few nanometers, namely the size of the free exciton Bohr radius. Our findings pave the way for direct writing of sub-10 nm nanoscale valleytronic devices and circuits using focused helium ions.

arXiv comment9 pages, 5 figures

References in corpus (14)

• Atomically thin MoS2: A new direct-gap semiconductor
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Local strain engineering in atomically thin MoS2
• Strong Photoluminescence Enhancement of MoS2 through Defect Engineering and Oxygen Bonding
• Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Low-temperature photocarrier dynamics in monolayer MoS2
• Carrier and polarization dynamics in monolayer MoS2
• Defect-induced conductivity anisotropy in MoS2 monolayers
• Photogating of mono- and few-layer MoS2
• Ultra-low power threshold for laser induced changes in optical properties of 2D Molybdenum dichalcogenides

Cited by in corpus (20)

• Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides with experiment and theory
• Atomistic defect states as quantum emitters in monolayer MoS${}_2$
• Large spin-orbit splitting of deep in-gap defect states of engineered sulfur vacancies in monolayer WS2
• Microsecond Valley Lifetime of Defect-Bound Excitons in Monolayer WSe${}_2$
• How Substitutional Point Defects in Two-Dimensional WS${}_2$ Induce Charge Localization, Spin-Orbit Splitting, and Strain
• Intrinsic and Extrinsic Defect-related Excitons in TMDCs
• Scalable single-photon sources in atomically thin MoS2
• Probing defects and spin-phonon coupling in CrSBr via resonant Raman scattering
• Condensation signatures of photogenerated interlayer excitons in a van der Waals heterostack
• Defect Sizing, Separation and Substrate Effects in Ion-Irradiated Monolayer 2D Materials
• Influence of Defects on the Valley Polarization Properties of Monolayer MoS${}_2$ Grown by Chemical Vapor Deposition
• Extrinsic localized excitons in patterned 2D semiconductors
• Tunable magneto-optical properties in MoS${}_2$ via defect-induced exciton transitions
• Electronic Properties of Defective MoS${}_2$ Monolayers Subject to Mechanical Deformations: A First-Principles Approach
• Defect-Moderated Oxidative Etching of MoS2
• Creation and Microscopic Origins of Single-Photon Emitters in Transition Metal Dichalcogenides and Hexagonal Boron Nitride
• Suppression of the Shear Raman Mode in Defective Bilayer MoS2
• Scalable transparent conductive thin films with electronically passive interfaces for direct chemical vapor deposition of 2D materials
• Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides
• Ultra-Sensitive Extinction Measurements of Optically Active Defects in Monolayer MoS${}_2$