Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral heterostructures encapsulated in hexagonal boron nitride

Abstract

Chemical vapor deposition (CVD) allows lateral edge epitaxy of transition metal dichalcogenide heterostructures with potential applications in optoelectronics. Critical for carrier and exciton transport is the quality of the two materials that constitute the monolayer and the nature of the lateral heterojunction. Important details of the optical properties were inaccessible in as-grown heterostructure samples due to large inhomogeneous broadening of the optical transitions. Here we perform optical spectroscopy at T = 4 K and also at 300 K to access the optical transitions in CVD grown MoSe2-WSe2 lateral heterostructures that are transferred from the growth-substrate and are encapsulated in hBN. Photoluminescence (PL), reflectance contrast and Raman spectroscopy reveal considerably narrowed optical transition linewidth similar to high quality exfoliated monolayers. In high-resolution transmission electron microscopy (HRTEM) we find near-atomically sharp junctions with a typical extent of 3nm for the covalently bonded MoSe2-WSe2. In PL imaging experiments we find effective excitonic diffusion length that are longer for WSe2 than for MoSe2 at low T=4 K, whereas at 300 K this trend is reversed.

Main and supplement

References in corpus (12)

• 2D materials and van der Waals heterostructures
• Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
• Moiré heterostructures as a condensed matter quantum simulator
• Sequential Edge-Epitaxy in 2D Lateral Heterostructures
• Atomically thin mirrors made of monolayer semiconductors
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Large-Scale Arrays of Single- and Few-Layer MoS2 Nanomechanical Resonators
• One pot chemical vapor deposition of high optical quality large area monolayer Janus transition metal dichalcogenides
• Interlayer Exciton Diode and Transistor
• Magneto-spectroscopy of exciton Rydberg states in a CVD grown WSe2 monolayer
• Unveiling the optical emission channels of monolayer semiconductors coupled to silicon nanoantennas
• Direct Observation of Intravalley Phonon Scattering of 2s Excitons in MoSe${}_2$ and WSe${}_2$ Monolayers

Cited by in corpus (11)

• Exciton optics, dynamics and transport in atomically thin semiconductors
• Interface engineering of charge-transfer excitons in 2D lateral heterostructures
• Kapitza-resistance-like exciton dynamics in atomically flat MoSe${}_2$-WSe${}_2$ lateral heterojunction
• Electrically Controlled Interfacial Charge Transfer Induced Excitons in MoSe2-WSe2 Lateral Heterostructure
• Dimensional reduction from magnetic field in moiré superlattices
• Impact of charge transfer excitons on unidirectional exciton transport in lateral TMD heterostructures
• Hyperspectral photoluminescence and reflectance microscopy of 2D materials
• Two dimensional semiconductors: optical and electronic properties
• Quantum Confined Luminescence in Two dimensions
• Trion Engineered Multimodal Transistors in Two dimensional Bilayer Semiconductor Lateral Heterostructures
• Electron density control in tungsten diselenide monolayers via photochlorination