Ultrafast Spontaneous Emission from a Slot-Antenna Coupled WSe₂ Monolayer

Abstract

Optical antennas can enhance the spontaneous emission rate from nanoemitters by orders of magnitude, enabling the possibility of an ultrafast, efficient, nanoscale LED. Semiconductors would be the preferred material for such a device to allow for direct high-speed modulation. However, efficient nanoscale devices are challenging to implement because of high surface recombination typical of most III−V materials. Monolayer transition metal dichalcogenides are an attractive alternative to a III−V emitter due to their intrinsically nanoscale dimensions, direct bandgap, and nearideal surfaces resulting in high intrinsic quantum yield. In this work, we couple a nanostrip (30 nm × 250 nm) monolayer of WSe 2 to a cavity-backed optical slot antenna through a self-aligned fabrication process. Photoluminescence, scattering, and lifetime measurements are used to estimate a radiative spontaneous emission rate enhancement of 318× from WSe 2 monolayers coupled to on-resonance antennas. Such a huge increase in the spontaneous emission rate results in an ultrafast radiative recombination rate and a quantum yield in nanopatterned monolayers comparable to unprocessed exfoliated flakes of WSe 2 .

Unidirectional, Ultrafast, and Bright Spontaneous Emission Source Enabled By a Hybrid Plasmonic Nanoantenna

“…Typical optical nanoemitters such as organic molecules, semiconductor quantum dots, solid state defects, and 2D materials are playing fundamental roles in the field of nanophotonics and quantum technology. However, the intrinsic lifetime of spontaneous emission is usually on nanosecond level, which limits the speed of optical devices that are needed in next‐generation optical interconnect and quantum communication, such as high‐speed nanoscale light emitting diodes (LEDs) and single photon sources .…”

A low cost plasmonic platform for photon emission engineering of two dimensional semiconductors

“…where, P rad is the far field radiated power which is collected over numerical aperture (NA) of the microscope (NA= 0.4) in presence of the nanocone structures. P tot and P o rad are the total power radiated by the dipole with and without the structure, respectively and η corresponds to the intrinsic PL quantum yield of the WSe 2 , taken with typical range of values from literature [24][25][26] as 0.001, 0.01 , 0.015, and 0.03.…”

Directional Emission from Tungsten Disulfide Monolayer Coupled to Plasmonic Nanowire‐on‐Mirror Cavity

“…For these purposes, many plasmonic structures, such as bowtie antenna, [ 31 ] nanodisk array, [ 32 ] nanocube, [ 29 ] nanoparticle, [ 30 ] and NW, [ 20,28 ] have been either fabricated over TMDs [ 33 ] or TMDs is transferred onto the structures. [ 34 ] Specifically, in the context of 2D materials, TMDs have been coupled to a single AgNW for studying remote SERS, [ 27 ] second‐harmonic generation, [ 35–38 ] logic operation, [ 39 ] Rabi splitting, [ 40 ] and plasmon–exciton interconversion. [ 20 ] Silver film–AgNW cavity has been recently utilized for the trion enhancement and enhancing the spin–orbit coupling.…”