Direct Optical-Structure Correlation in Atomically Thin Dichalcogenides and Heterostructures
arXiv:1910.13387 · doi:10.1007/s12274-019-2601-7
Abstract
Atomically thin transition metal dichalcogenides (TMDs) have distinct opto-electronic properties including enhanced luminescence and high on-off current ratios, which can be further modulated by making more complex TMD heterostructures. However, resolution limits of conventional optical methods do not allow for direct optical-structural correlation measurements in these materials, particularly of buried interfaces in TMD heterostructures. Here we use, for the first time, electron beam induced cathodoluminescence in a scanning transmission electron microscope (CL-STEM) to measure optical properties of monolayer TMDs (WS2, MoS2 and WSSe alloy) encapsulated between layers of hBN. We observe dark areas resulting from localized (~ 100 nm) imperfect interfaces and monolayer folding, which shows that the intimate contact between layers in this application-relevant heterostructure is required for proper inter layer coupling. We also realize a suitable imaging method that minimizes electron-beam induced changes and provides measurement of intrinsic properties. To overcome the limitation of small electron interaction volume in TMD monolayer (and hence low photon yield), we find that encapsulation of TMD monolayers with hBN and subsequent annealing is important. CL-STEM offers to be a powerful method to directly measure structure-optical correspondence in lateral or vertical heterostructures and alloys.
supplementary also included within file
References in corpus (16)
- Atomically thin MoS2: A new direct-gap semiconductor
- 2D materials and van der Waals heterostructures
- Boron nitride substrates for high-quality graphene electronics
- Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
- Bandgap Engineering of Strained Monolayer and Bilayer MoS2
- Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping
- Exciton Binding Energy of Monolayer WS2
- The hot pick-up technique for batch assembly of van der Waals heterostructures
- Intrinsic Exciton Linewidth in Monolayer Transition Metal Dichalcogenides
- Atomically thin p-n junctions based on two-dimensional materials
- Control of Radiation Damage in MoS2 by Graphene Encapsulation
- Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
- Density-Dependent Quantum Hall States and Zeeman Splitting in Monolayer and Bilayer WSe
- Photoluminescence of hexagonal boron nitride: effect of surface oxidation under UV-laser irradiation
- Efficient cathodoluminescence of monolayer transitional metal dichalcogenides in a van der Waals heterostructure
- Disorder Dependent Valley Properties in Monolayer WSe2
Cited by in corpus (8)
- Moiré and beyond in transition metal dichalcogenide twisted bilayers
- Nanoscale modification of WS trion emission by its local electromagnetic environment
- Controlled defect production in monolayer MoS2 via electron irradiation at ultralow accelerating voltages
- Cathodoluminescence spectroscopy of monolayer hexagonal boron nitride
- Nano-optics of transition metal dichalcogenides and their van der Waals heterostructures with electron spectroscopies
- Quantum light generation with ultra-high spatial resolution in 2D semiconductors via ultra-low energy electron irradiation
- Effect of electron-irradiation on layered quantum materials
- Quantum Confined Luminescence in Two dimensions