FIP Seminar: Tailoring light-matter interaction in 2D semiconductors using plasmonic nanocavities

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Wed, 03/22/2017 - 12:00 to 13:00


Jiani Huang, Chambers Scholar, Department of Physics, Duke University

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)]. Moreover, we show a strong modification of the PL emission peaks. Manipulating the optical properties of these two-dimensional materials using tunable plasmon resonances is promising for the design of novel optical devices with precisely tailored responses.  

Jiani Huang is a fifth-year Physics Ph.D. candidate working in the group of Prof. Maiken Mikkelsen. Her research focuses on ultrafast optical experiments to understand and control light-matter interactions at the nanoscale and in quantum-confined systems, leading the way to exploit quantum effects in future devices. In particular, her research interest is primarily on monolayer transition metal dichalcogenides (TMDCs), which is a new class of two-dimensional  materials that can be exfoliated in a similar manner to graphene. Additionally, Jiani is also involved in the nanofabrication and characterization of metallic film coupled plasmonic nanopatch antennas. Jiani received her B.S. degree in Physics from the Southeast University in China in 2012. Her previous awards include the President’s Scholarship award at Southeast University (2009), the GPNANO Fellowship at Duke University (2014), and John T. Chambers Scholar from Fitzpatrick Institute for Photonics at Duke University (2015-2017).