Viktoryia Shautsova1,2,Linlin Hou1,Qianyang Zhang1,Yang Lu1,Jamie Warner1,3
University of Oxford1,Stanford University2,The University of Texas at Austin3
Viktoryia Shautsova1,2,Linlin Hou1,Qianyang Zhang1,Yang Lu1,Jamie Warner1,3
University of Oxford1,Stanford University2,The University of Texas at Austin3
Monolayer 2D transition metal dichalcogenides (TMDCs) have recently emerged as promising materials for a new generation of optoelectronic devices due to their direct bandgaps and high light emitting efficiency. Further efficiency improvement and control of light emission from vertical heterostructures based on TMDCs have driven the development of various device architectures with photonic cavities with additional efforts to achieve lasing modes. Plasmonic gap structures present a particularly intriguing system due to tightly confined fields. Large field enhancements can be easily reached by positioning plasmonic nanoparticles on a metal film with a thin spacer layer or 2D materials. Such plasmonic nanocavities have been demonstrated to drastically enhance light emitting efficiency from TMDCs. In this work, we study the effect of plasmonic nanocavities on electrically induced light emission in vertical van der Waals heterostructures based on WS2 monolayers. The devices are fabricated from large-scale CVD materials allowing batch production of hundreds of devices in a single fabrication process. Every layer, including nanostructures, is aligned-transferred to avoid heat induced damage of WS2 layers during direct metal deposition. While being a transparent top electrode, graphene is employed to facilitate current injection in the active material WS<sub>2</sub>. Using hBN tunnelling barriers between graphene/gold contacts and WS<sub>2</sub> layers, the current leakage is minimised for efficient electron-to-photon conversion. In presence of plasmonic cavities, the devices demonstrate modified light emission spectra indicating the potential coupling with gap plasmon modes.