Non-Equilibrium First-Order Exciton Mott Transition at Monolayer Lateral Heterojunctions Visualized by Ultrafast Microscopy

Atomically precise lateral heterojunctions based on transition metal dichalcogenides provide a new platform for exploring exciton Mott transition in one-dimension. To investigate the intrinsically non-equilibrium Mott transition, we employed ultrafast microscopy with ~ 200 fs temporal resolution to...

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Bibliographic Details
Published in:arXiv.org 2021-11
Main Authors: Long, Yuan, Zheng, Biyuan, Zhao, Qiuchen, Kempt, Roman, Brumme, Thomas, Agnieszka Beata Kuc, Ma, Chao, Deng, Shibin, Pan, Anlian, Huang, Libai
Format: Article
Language:English
Subjects:
Electrons
Equilibrium
Excitons
Heterojunctions
Heterostructures
Holes (electron deficiencies)
Microscopy
Room temperature
Temporal resolution
Transition metal compounds
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Summary:Atomically precise lateral heterojunctions based on transition metal dichalcogenides provide a new platform for exploring exciton Mott transition in one-dimension. To investigate the intrinsically non-equilibrium Mott transition, we employed ultrafast microscopy with ~ 200 fs temporal resolution to image the transport of different exciton phases in a type II WSe2-WS1.16Se0.84 lateral heterostructure. These measurements visualized the extremely rapid expansion of a highly non-equilibrium electron-hole (e-h) plasma phase with a Fermi velocity up to 3.2*10^6 cm*s-1. An abrupt first-order exciton Mott transition at a density of ~ 5*10^12 cm-2 at room temperature was revealed by ultrafast microscopy, which could be disguised as a continuous transition in conventional steady-state measurements. These results point to exciting new opportunities for designing atomically thin lateral heterojunctions as novel highways of excitons and collective e-h plasma for high-speed electronic applications.
ISSN:2331-8422