Spin-orbit engineering in transition metal dichalcogenide alloy monolayers

Abstract

Transition metal dichalcogenide (TMDC) monolayers are newly discovered semiconductors for a wide range of applications in electronics and optoelectronics. Most studies have focused on binary monolayers that share common properties: direct optical bandgap, spin-orbit (SO) splittings of hundreds of meV, light-matter interaction dominated by robust excitons and coupled spin-valley states of electrons. Studies on alloy-based monolayers are more recent, yet they may not only extend the possibilities for TMDC applications through specific engineering but also help understanding the differences between each binary material. Here, we synthesized highly crystalline Mo${}_{(1-x)}$W${}_x$Se${}_2$ to show engineering of the direct optical bandgap and the SO coupling in ternary alloy monolayers. We investigate the impact of the tuning of the SO spin splitting on the optical and polarization properties. We show a non-linear increase of the optically generated valley polarization as a function of tungsten concentration, where 40% tungsten incorporation is sufficient to achieve valley polarization as high as in binary WSe2. We also probe the impact of the tuning of the conduction band SO spin splitting on the bright versus dark state population i.e. PL emission intensity. We show that the MoSe2 PL intensity decreases as a function of temperature by an order of magnitude, whereas for WSe2 we measure surprisingly an order of magnitude increase over the same temperature range (T=4-300K). The ternary material shows a trend between these two extreme behaviors. These results show the strong potential of SO engineering in ternary TMDC alloys for optoelectronics and applications based on electron spin- and valley-control.

5 pages, 3 figures + supplement

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Cited by in corpus (76)

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• Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons
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• Splitting between Bright and Dark excitons in Transition Metal Dichalcogenide Monolayers
• Photonic-Crystal Exciton-Polaritons in Monolayer Semiconductors
• Room temperature Tamm-Plasmon Exciton-Polaritons with a WSe2 monolayer
• Revealing the Biexciton and Trion-exciton Complexes in BN Encapsulated WSe2
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Optical properties of atomically thin transition metal dichalcogenides: Observations and puzzles
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• Interlayer exciton dynamics in a dichalcogenide monolayer heterostructure
• Measurement of the Spin-Forbidden Dark Excitons in MoS2 and MoSe2 monolayers
• Resonance effects in the Raman scattering of mono- and few layers MoSe${}_2$
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• Optical response of monolayer, few-layer and bulk tungsten disulfide
• Strong coupling between excitons in transition metal dichalcogenides and optical bound states in the continuum
• Discrete quantum dot like emitters in monolayer MoSe2: Spatial mapping, Magneto-optics and Charge tuning
• Bosonic condensation of exciton-polaritons in an atomically thin crystal
• Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure
• Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers
• Localized bright luminescence of indirect excitons and trions in MoSe${}_2$/WSe${}_2$ van der Waals heterostructure
• Excitonic properties of semiconducting monolayer and bilayer MoTe2
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• Spin-orbit coupling induced valley Hall effects in transition-metal dichalcogenides
• Probing and manipulating valley coherence of dark excitons in monolayer WSe${}_2$
• Symmetry regimes for circular photocurrents in monolayer MoSe2
• Probing Many-Body Interactions in Monolayer Transition-Metal Dichalcogenides
• Dark trions govern the temperature-dependent optical absorption and emission of doped atomically thin semiconductors
• Spin-Orbit Logic with Magnetoelectric Nodes: A Scalable Charge Mediated Nonvolatile Spintronic Logic
• Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
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• Electronic bandstructure and van der Waals coupling of ReSe2 revealed by high-resolution angle-resolved photoemission spectroscopy
• Chemical trends of deep levels in van der Waals semiconductors
• Excitation-induced transition to indirect band gaps in atomically thin transition metal dichalcogenide semiconductors
• Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides
• Prominent room temperature valley polarization in WS2/graphene heterostructures grown by chemical vapor deposition
• Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral heterostructures encapsulated in hexagonal boron nitride
• Spin States Protected from Intrinsic Electron-Phonon-Coupling Reaching 100 ns Lifetime at Room Temperature in MoSe${}_2$
• Visualizing Orbital Content of Electronic Bands in Anisotropic 2D Semiconducting ReSe${}_2$
• Observation of bright and dark exciton transitions in monolayer MoSe2 by photocurrent spectroscopy
• Efficient method for calculating Raman spectra of solids with impurities and alloys and its application to two-dimensional transition metal dichalcogenides
• Dark-exciton based strain sensing in transition metal dichalcogenides
• Exciton-phonon relaxation bottleneck and radiative decay of thermal exciton reservoir in two-dimensional materials
• Valley Degree of Freedom in Two-Dimensional van der Waals Materials
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• Magneto-spectroscopy of exciton Rydberg states in a CVD grown WSe2 monolayer
• Voltage-controlled long-range propagation of indirect excitons in van der Waals heterostructure
• Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
• Electric Dipole Spin Resonance of 2D Semiconductor Spin Qubits
• Nontrivial doping evolution of electronic properties in Ising-superconducting alloys
• Unveiling the optical emission channels of monolayer semiconductors coupled to silicon nanoantennas
• The optical response of artificially twisted MoS${}_2$ bilayers
• Engineering 2D material exciton lineshape with graphene/h-BN encapsulation
• Pulsed thermal deposition of binary and ternary transition metal dichalcogenide monolayers and heterostructures
• Transition from band insulator to excitonic insulator via alloying Se into Monolayer TiS${}_3$: A Computational Study
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• Ultrafast Chirality-dependent Dynamics from Helicity-resolved Transient Absorption Spectroscopy
• Valley Phenomena in the Candidate Phase Change Material WSe${}_{2(1-x)}$Te${}_{2x}$
• Strong In-plane Anisotropy in the Electronic Properties of Doped Transition Metal Dichalcogenides exhibited in W1-xNbxS2
• Spin-orbit-stable type-II nodal line band crossing in n-doped monolayer MoX2 (X=S,Se,Te)
• Extrinsic n-type semiconductor transition in ZrSe2 with the metallic character through hafnium substitution
• Alloying-induced topological transition in 2D transition-metal dichalcogenide semiconductors
• Hyperspectral photoluminescence and reflectance microscopy of 2D materials
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• Valley spin-acoustic resonance in MoS${}_2$ monolayers
• Temperature-dependent Optical and Polaritonic Properties of hBN-encapsulated Monolayer TMDs
• Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states
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• High-temperature observation of intralayer, interlayer, and Rydberg excitons in bulk van der Waals alloy single crystals