Please use this identifier to cite or link to this item: https://doi.org/10.1088/2053-1583/aadf40
Title: Tunable bright interlayer excitons in few-layer black phosphorus based van der Waals heterostructures
Authors: Chen, Yifeng 
Quek, Su Ying 
Keywords: Science & Technology
Technology
Materials Science, Multidisciplinary
Materials Science
interlayer excitons
heterostructures
2D materials
black phosphorus
optical properties
hexagonal boron nitride
germanium sulfide
ELECTRONIC-PROPERTIES
BAND-GAP
SEMICONDUCTOR
TRANSPORT
GRAPHENE
OPTOELECTRONICS
Issue Date: 1-Oct-2018
Publisher: IOP PUBLISHING LTD
Citation: Chen, Yifeng, Quek, Su Ying (2018-10-01). Tunable bright interlayer excitons in few-layer black phosphorus based van der Waals heterostructures. 2D MATERIALS 5 (4). ScholarBank@NUS Repository. https://doi.org/10.1088/2053-1583/aadf40
Abstract: © 2018 IOP Publishing Ltd. Few-layer black phosphorus (BP) is a direct band gap material with large exciton binding energies, and shows great promise in optoelectronic applications. Here, we study the excitons in BP-based heterostructures with encapsulation and spacer 2D layers, using first principles GW and Bethe- Salpeter equation (BSE) methods. The 2D layers chosen are germanium sulfide (GeS) and hexagonal boron nitride (hBN), representing respectively strong and weak hybridization with BP. Except for hBN-encapsulated BP, all systems host bright interlayer (or indirect) excitons. In contrast to 2D indirect gap heterostructures, the interlayer excitons here are much brighter. Strong hybridization between GeS and BP increases the effective mass and room temperature exciton lifetimes. In contrast, the hBN spacer layer decouples the BP monolayers in BP/hBN/BP, resulting in the lowest energy exciton being dark. Surprisingly, however, BP/hBN/BP hosts interlayer BP excitons that are even brighter than those in bilayer BP. This lowest energy bright exciton lies very close in energy to the dark state, resulting in an increased effective lifetime. Our work uncovers the interplay between interlayer interactions and the physics of interlayer excitons, and paves the way for the use of bottomup materials design to optimize the dipole oscillator strengths and lifetimes of interlayer excitons for excitonic device applications.
Source Title: 2D MATERIALS
URI: https://scholarbank.nus.edu.sg/handle/10635/170893
ISSN: 20531583
DOI: 10.1088/2053-1583/aadf40
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