Radiative control of localized excitons at room temperature with an ultracompact tip-enhanced plasmonic nano-cavity

In atomically thin semiconductors, localized exciton (X\(_L\)) coupled to light shows single quantum emitting behaviors through radiative relaxation processes providing a new class of optical sources for potential applications in quantum communication. In most studies, however, X\(_L\) photoluminesc...

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Published inarXiv.org
Main Authors Lee, Hyeongwoo, Kim, Inki, Park, Chulho, Kang, Mingu, Mun, Jungho, Kim, Yeseul, Raschke, Markus B, Jeong, Mun Seok, Rho, Junsuk, Kyoung-Duck Park
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 14.09.2020
Subjects
Antennas
Crystal defects
Emissions control
Excitons
Photoluminescence
Plasmonics
Radius of curvature
Room temperature
Semiconductors
Spatial resolution
Stability
Tensile strain
Tips
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Summary:In atomically thin semiconductors, localized exciton (X\(_L\)) coupled to light shows single quantum emitting behaviors through radiative relaxation processes providing a new class of optical sources for potential applications in quantum communication. In most studies, however, X\(_L\) photoluminescence (PL) from crystal defects has mainly been observed in cryogenic conditions because of their sub-wavelength emission region and low quantum yield at room temperature. Furthermore, engineering the radiative relaxation properties, e.g., emission region, intensity, and energy, remained challenging. Here, we present a plasmonic antenna with a triple-sharp-tips geometry to induce and control the X\(_L\) emission of a WSe\(_2\) monolayer (ML) at room temperature. By placing a ML crystal on the two sharp Au tips in a bowtie antenna fabricated through cascade domino lithography with a radius of curvature of <1 nm, we effectively induce tensile strain in the nanoscale region to create robust X\(_L\) states. An Au tip with tip-enhanced photoluminescence (TEPL) spectroscopy is then added to the strained region to probe and control the X\(_L\) emission. With TEPL enhancement of X\(_L\) as high as ~10\(^6\) in the triple-sharp-tips device, experimental results demonstrate the controllable X\(_L\) emission in <30 nm area with a PL energy shift up to 40 meV, resolved by tip-enhanced PL and Raman imaging with <15 nm spatial resolution. Our approach provides a systematic way to control localized quantum light in 2D semiconductors offering new strategies for active quantum nano-optical devices.
ISSN:2331-8422