Enhanced Light Emission from Monolayer MoS2 by Doubly Resonant Spherical Si Nanoantennas

Optical antennas provide a powerful tool to control local photonic environments and enhance light emission from two-dimensional transition-metal dichalcogenides. Dielectric nanoantennas with multipolar Mie resonances bring unique advantages for achieving simultaneous enhancement of the absorption and emission processes. Here, we achieve a strong modification of the photoluminescence (PL) behavior of monolayer MoS2 by a spherical nanoparticle (NP) of crystalline silicon (Si) that works as a double resonance nanoantenna. From theoretical calculations for in-plane dipoles placed beneath a Si NP nanoantenna with different sizes, we explore optimal conditions for the double resonances. Then, we develop a heterostructure composed of a Si NP and a monolayer MoS2 sheet with a comparable diameter and investigate the scattering, PL, and PL excitation spectra across a wide Si NP size range. We show that the spectral shape is significantly modified and PL intensity is enhanced up to ∼10-fold due to the coupling of the excitation process to the magnetic quadrupole resonance and the emission process to the magnetic dipole resonance.