Quantum tunneling high-speed nano-excitonic modulator.

Lee, Hyeongwoo; Kim, Sujeong; Eom, Seonhye; Ji, Gangseon; Choi, Soo Ho; Joo, Huitae; Bae, Jinhyuk; Kim, Ki Kang et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

High-speed electrical control of nano-optoelectronic properties in two-dimensional semiconductors is a building block for the development of excitonic devices, allowing the seamless integration of nano-electronics and -photonics. Here, we demonstrate a high-speed electrical modulation of nanoscale exciton behaviors in a MoS<sub>2</sub> monolayer at room temperature through a quantum tunneling nanoplasmonic cavity. Electrical control of tunneling electrons between Au tip and MoS<sub>2</sub> monolayer facilitates the dynamic switching of neutral exciton- and trion-dominant states at the nanoscale. Through tip-induced spectroscopic analysis, we locally characterize the modified recombination dynamics, resulting in a significant change in the photoluminescence quantum yield. Furthermore, by obtaining a time-resolved second-order correlation function, we demonstrate that this electrically-driven nanoscale exciton-trion interconversion achieves a modulation frequency of up to 8 MHz. Our approach provides a versatile platform for dynamically manipulating nano-optoelectronic properties in the form of transformable excitonic quasiparticles, including valley polarization, recombination, and transport dynamics.