Controlling the interaction between light and matter is critical for the performance of optoelectronic and nanophotonic devices. Two-dimensional transition metal dichalcogenides (TMDCs) offers an ideal platform for a wide range of applications due to their remarkable optical properties. However, atomically thin TMDC monolayers suffer from weak light absorption (~3 %) and low photoluminescence (PL) quantum yield (~0.4 %). Furthermore, among the complex excitonic states of monolayer TMDCs, the B exciton emission is inherently weak compared to the dominant A exciton emission. In this talk, I will describe our recent experiments utilizing tunable plasmonic nanocavities, where emitters are sandwiched in a sub-10-nm dielectric gap between a metallic film and colloidally synthesized silver nanocubes. When emitters are embedded in the gap region, the spontaneous emission rate enhancements can be exceeding 1,000 times while maintaining high quantum efficiency (>50 %) and directional emission [Akselrod et al. Nature Photonics 8, 835 (2014)]. Incorporating semiconductor quantum dots into the plasmonic cavity enable ultrafast spontaneous emission with emission rates exceeding 90 GHz [Hoang et al. Nature Communications 6, 7788 (2015)]. When MoS2 monolayers are integrated into the plasmonic nanocavities with tunable plasmon resonances, we observe a 1,200-fold enhancement for A exciton emission and a 6,100-fold enhancement for B exciton emission [Huang et al. Submitted (2017)].
FIP Seminar: Tailoring light-matter interaction in 2D semiconductors using plasmonic nanocavities
Jiani Huang, Chambers Scholar, Department of Physics, Duke University
Wednesday, March 22, 2017 - 12:00pm
Hudson Hall 125