Overbias Photon Emission from Light-Emitting Devices Based on Monolayer Transition Metal Dichalcogenides.

Shan, Shengyu; Huang, Jing; Papadopoulos, Sotirios; Khelifa, Ronja; Taniguchi, Takashi; Watanabe, Kenji; Wang, Lujun; Novotny, Lukas · Nano Lett · 2023

basic_science · Level V

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Abstract

Tunneling light-emitting devices (LEDs) based on transition metal dichalcogenides (TMDs) and other two-dimensional (2D) materials are a new platform for on-chip optoelectronic integration. Some of the physical processes underlying this LED architecture are not fully understood, especially the emission at photon energies higher than the applied electrostatic potential, so-called overbias emission. Here we report overbias emission for potentials that are near half of the optical bandgap energy in TMD-based tunneling LEDs. We show that this emission is not thermal in nature but consistent with exciton generation via a two-electron coherent tunneling process.