Please use this identifier to cite or link to this item: https://doi.org/10.1088/2053-1583/ab1e06
Title: Dielectric screening by 2D substrates
Authors: Noori, Keian 
Cheng, Nicholas Lin Quan
Xuan, Fengyuan 
Quek, Su Ying 
Keywords: Science & Technology
Technology
Materials Science, Multidisciplinary
Materials Science
2D materials
Screening
Boron nitride
Band gap renormalization
DENSITY-FUNCTIONAL APPROACH
QUASI-PARTICLE
GRAPHENE
SEMICONDUCTORS
MATRICES
Issue Date: 1-Jul-2019
Publisher: IOP PUBLISHING LTD
Citation: Noori, Keian, Cheng, Nicholas Lin Quan, Xuan, Fengyuan, Quek, Su Ying (2019-07-01). Dielectric screening by 2D substrates. 2D MATERIALS 6 (3). ScholarBank@NUS Repository. https://doi.org/10.1088/2053-1583/ab1e06
Abstract: © 2019 IOP Publishing Ltd. Two-dimensional (2D) materials are increasingly being used as active components in nanoscale devices. Many interesting properties of 2D materials stem from the reduced and highly non-local electronic screening in two dimensions. While electronic screening within 2D materials has been studied extensively, the question still remains of how 2D substrates screen charge perturbations or electronic excitations adjacent to them. Thickness-dependent dielectric screening properties have recently been studied using electrostatic force microscopy (EFM) experiments. However, it was suggested that some of the thickness-dependent trends were due to extrinsic effects. Similarly, Kelvin probe measurements (KPM) indicate that charge fluctuations are reduced when BN slabs are placed on SiO2, but it is unclear if this effect is due to intrinsic screening from BN. In this work, we use first principles calculations to study the fully non-local dielectric screening properties of 2D material substrates. Our simulations give results in good qualitative agreement with those from EFM experiments, for hexagonal boron nitride (BN), graphene and MoS2, indicating that the experimentally observed thickness-dependent screening effects are intrinsic to the 2D materials. We further investigate explicitly the role of BN in lowering charge potential fluctuations arising from charge impurities on an underlying SiO2 substrate, as observed in the KPM experiments. 2D material substrates can also dramatically change the HOMO-LUMO gaps of adsorbates, especially for small molecules, such as benzene. We propose a reliable and very quick method to predict the HOMO-LUMO gaps of small physisorbed molecules on 2D and 3D substrates, using only the band gap of the substrate and the gas phase gap of the molecule.
Source Title: 2D MATERIALS
URI: https://scholarbank.nus.edu.sg/handle/10635/170974
ISSN: 20531583
DOI: 10.1088/2053-1583/ab1e06
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