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

doi:10.1039/d2na00495j

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

Chair of Physics (460)

Research output: Contribution to journal › Article › Research › peer-review

Abstract

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 language	English
Number of pages	7
Journal	Nanoscale advances
Volume	2022
Issue number	23
DOIs	https://doi.org/10.1039/d2na00495j
Publication status	E-pub ahead of print - 25 Oct 2022

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Publisher Copyright: © The Royal Society of Chemistry 2022.

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abstract = "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 byelectron 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.",

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

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T1 - Exciton tuning in monolayer WSe2 via substrate induced electron doping

AU - Pan, Yang

AU - Rahaman, Mahfujur

AU - He, Lu

AU - Milekhin, Ilya

AU - Manoharan, Gopinath

AU - Aslam, Muhammad Awais

AU - Blaudeck, Thomas

AU - Willert, Andreas

AU - Matkovic, Aleksandar

AU - Madeira, Teresa I.

AU - Zahn, Dietrich R.T.

PY - 2022/10/25

Y1 - 2022/10/25

N2 - 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 byelectron 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.

AB - 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 byelectron 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.

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DO - 10.1039/d2na00495j

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SN - 2516-0230

VL - 2022

JO - Nanoscale advances

JF - Nanoscale advances

IS - 23

ER -

Exciton tuning in monolayer WSe2 via substrate induced electron doping

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