Single Photon Emitters in Monolayer Semiconductors Coupled to Transition Metal Dichalcogenide Nanoantennas on Silica and Gold Substrates
Panaiot G. Zotev, Sam A. Randerson, Xuerong Hu, Yue Wang, Alexander I. TartakovskiiABSTRACT
Single photon emitters (SPEs) in transition metal dichalcogenide (TMD) monolayers are attractive for quantum information applications. Strain in the monolayer, induced by underlying Mie resonators, localizes SPEs to positions co‐located with photonic hotspots, providing control over their optical properties. However, resonators made from traditional materials such as silicon or gallium phosphide (GaP), often require a high refractive index substrate resulting in light losses and limited photonic enhancement. Here, we use nanoantennas (NAs) fabricated from a multilayer TMD WS 2 , allowing complete flexibility with the choice of substrate due to the adhesive van der Waals forces, enabling high refractive index contrast or the use of highly reflective metallic surfaces. We demonstrate formation of SPEs in WSe 2 monolayers transferred onto WS 2 NAs on both SiO 2 and Au substrates, enabling strong photonic enhancements and increased single photon collection. We find enhancement of quantum efficiencies (QE) averaging to 43% (7%) for SPEs on WS 2 NAs on a SiO 2 (Au) substrate. We further combine the advantages offered by both dielectric and metallic substrates to numerically simulate an optimized NA geometry for maximum WSe 2 single photon excitation, emission and collection yielding fluorescence enhancements of over 4 (5) orders of magnitude compared to vacuum (flat SiO 2 /Si surface).