Nano-optical imaging of monolayer MoSe2-WSe2 lateral heterostructure

Abstract

Near-field optical microscopy can be used as a viable route to understand the nanoscale material properties below the diffraction limit. On the other hand, atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs) are the materials of recent interest to study the spatial confinement of charge carriers, photon, and phonons. Heterostructures based on Mo or W based monolayer TMDs form type-II band alignment, and hence the optically excited carriers can be easily separated for applications pertaining to photonics and electronics. Mapping these spatially confined carriers or photons in a heterostructure with nanoscale resolution as well as their recombination behavior at the interfaces are necessary for the effective use of these materials in future high performance optoelectronics. We performed tip-enhanced photoluminescence (TEPL) imaging to increase the spatial resolution on multi-junction monolayer MoSe2-WSe2 lateral heterostructures grown by chemical vapor deposition (CVD) method. The near-field nano-PL emission map was used to distinguish the presence of distinct crystalline boundaries and the heterogeneities across the interfaces. This method significantly improves the nanoscale resolution of 2D materials, especially for understanding the PL emission properties at the vicinity of hetero-interfaces.

References in corpus (11)

• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Two-Dimensional Material Nanophotonics
• Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Optoelectronics with electrically tunable PN diodes in a monolayer dichalcogenide
• Solar-energy conversion and light emission in an atomic monolayer p-n diode
• Band alignment of two-dimensional transition metal dichalcogenides: application in tunnel field effect transistors
• Sequential Edge-Epitaxy in 2D Lateral Heterostructures
• Ultrafast and spatially resolved studies of charge carriers in atomically-thin molybdenum disulfide
• Hybrid tip-enhanced nano-spectroscopy and -imaging of monolayer WSe2 with local strain control
• Nano-optical imaging of monolayer MoSe2 using tip-enhanced photoluminescence