Electrical control of anisotropic and tightly bound excitons in bilayer phosphorene

Monolayer and few-layer phosphorene are anisotropic quasi-two-dimensional (quasi-2D) van der Waals (vdW) semiconductors with the linear-dichroic light-matter interaction and the widely tunable direct band gap in the infrared frequency range. Despite recent theoretical predictions of strongly bound e...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. B 2021-01, Vol.103 (4), p.1, Article L041407
Main Authors: Yoon, Sangho, Kim, Taeho, Seo, Seung-Young, Shin, Seung-Hyun, Song, Su-Beom, Kim, B. J., Watanabe, Kenji, Taniguchi, Takashi, Lee, Gil-Ho, Jo, Moon-Ho, Qiu, Diana Y., Kim, Jonghwan
Format: Article
Language:English
Subjects:
Anisotropy
Bilayers
Boron nitride
Dichroism
Elementary excitations
Encapsulation
Energy gap
Excitation spectra
Excitons
Field effect transistors
Frequency ranges
Monolayers
Optical properties
Optical resonance
Optoelectronics
Oxidation
Phosphorene
Photoluminescence
Rydberg series
Semiconductor devices
Spectrum analysis
Trions
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Monolayer and few-layer phosphorene are anisotropic quasi-two-dimensional (quasi-2D) van der Waals (vdW) semiconductors with the linear-dichroic light-matter interaction and the widely tunable direct band gap in the infrared frequency range. Despite recent theoretical predictions of strongly bound excitons with unique properties, it remains experimentally challenging to probe excitonic quasiparticles due to the severe oxidation that occurs during device fabrication. In this study, we report the observation of strongly bound excitons and trions with highly anisotropic optical properties in intrinsic bilayer phosphorene, which are protected from oxidation by encapsulation with hexagonal boron nitride (hBN) in a field-effect transistor (FET) geometry. Reflection contrast and photoluminescence spectroscopy clearly reveal the linear-dichroic optical spectra from anisotropic excitons and trions in the hBN-encapsulated bilayer phosphorene. The optical resonances from the exciton Rydberg series indicate that the neutral exciton binding energy is over 100 meV even with the dielectric screening from hBN. The electrostatic injection of free holes enables an additional optical resonance from a positive trion (charged exciton) ∼30 meV below the optical band gap of the charge-neutral system. Our work shows exciting possibilities for monolayer and few-layer phosphorene as a platform to explore many-body physics and photonics and optoelectronics based on strongly bound excitons with twofold anisotropy.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.103.L041407