We report on large exciton tuning in WSe2 monolayers via substrate induced non-degenerate doping. We observe a redshift of ∼62 meV for the A exciton together with a 1-2 orders of magnitude photoluminescence (PL) quenching when the monolayer WSe2 is brought in contact with highly oriented pyrolytic graphite (HOPG) compared to the dielectric substrates such as hBN and SiO2. As the evidence of doping from HOPG to WSe2, a drastic increase of the trion emission intensity was observed. Using a systematic PL and Kelvin probe force microscopy (KPFM) investigation on WSe2/HOPG, WSe2/hBN, and WSe2/graphene, we conclude that this unique excitonic behavior is induced by electron doping from the substrate. Our results propose a simple yet efficient way for exciton tuning in monolayer WSe2, which plays a central role in the fundamental understanding and further device development.
@article{arxiv.2207.02993,
title = {Exciton tuning in monolayer WSe$_2$ via substrate induced electron doping},
author = {Yang Pan and Mahfujur Rahaman and Lu He and Ilya Milekhin and Gopinath Manoharan and Muhammad Awais Aslam and Thomas Blaudeck and Andreas Willert and Aleksandar Matković and Teresa I. Madeira and Dietrich R. T. Zahn},
journal= {arXiv preprint arXiv:2207.02993},
year = {2022}
}