Understanding and controlling the nanoscale transport of excitonic quasiparticles in atomically thin 2D semiconductors is crucial to produce highly efficient nano-excitonic devices. Here, we present a nano-gap device to selectively confine excitons or trions of 2D transition metal dichalcogenides at the nanoscale, facilitated by the drift-dominant exciton funnelling into the strain-induced local spot. We investigate the spatio-spectral characteristics of the funnelled excitons in a WSe2 monolayer (ML) and converted trions in a MoS2 ML using hyperspectral tip-enhanced photoluminescence (TEPL) imaging with <15 nm spatial resolution. In addition, we dynamically control the exciton funnelling and trion conversion rate by the GPa scale tip pressure engineering. Through a drift-diffusion model, we confirm an exciton funnelling efficiency of ~25 % with a significantly low strain threshold (~0.1 %) which sufficiently exceeds the efficiency of ~3 % in previous studies. This work provides a new strategy to facilitate efficient exciton transport and trion conversion of 2D semiconductor devices.
@article{arxiv.2109.09713,
title = {Low-threshold exciton transport and control in atomically thin semiconductors},
author = {Hyeongwoo Lee and Yeonjeong Koo and Jinseong Choi and Shailabh Kumar and Hyoung-Taek Lee and Gangseon Ji and Soo Ho Choi and Mingu Kang and Ki Kang Kim and Hyeong-Ryeol Park and Hyuck Choo and Kyoung-Duck Park},
journal= {arXiv preprint arXiv:2109.09713},
year = {2021}
}