Exciton tuning in monolayer WSe2 via substrate induced electron doping

Yang Pan, Mahfujur Rahaman, Lu He, Ilya Milekhin, Gopinath Manoharan, Muhammad Awais Aslam, Thomas Blaudeck, Andreas Willert, Aleksandar Matkovic, Teresa I. Madeira, Dietrich R.T. Zahn

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We report 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 dielectric substrates such as hBN and SiO2. As the evidence of doping from HOPG to WSe2, a drastic increase of the intensity ratio of trions to neutral excitons 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.
Original languageEnglish
Number of pages7
JournalNanoscale advances
Issue number23
Publication statusE-pub ahead of print - 25 Oct 2022

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