Substrate effects on the exciton fine structure of black phosphorus quantum dots

J. S. De Sousa, M. A. Lino, D. R. Da Costa, A. Chaves, J. M. Pereira, G. A. Farias

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8 Scopus citations

Abstract

We study the size-dependent exciton fine structure in monolayer black phosphorus quantum dots (BPQDs) deposited on different substrates (isolated, Si, and SiO2) using a combination of the tight-binding method to calculate single-particle states and the configuration interaction formalism to determine the excitonic spectrum. We demonstrate that the substrate plays a dramatic role in the excitonic gaps and excitonic spectrum of the QDs. For reasonably high dielectric constants (sub∼ Si=11.70), the excitonic gap can be described by a single power law EX(R)=EX(bulk)+C/Rγ. For low dielectric constants sub≤ SiO2=3.90, the size dependence of the excitonic gaps requires the sum of two power laws EX(R)=Eg(bulk)+A/Rn-B/Rm to describe both strong and weak quantum confinement regimes, where A, B, C, γ, n, and m are substrate-dependent parameters. We also predict that the exciton lifetimes exhibit a strong temperature dependence, ranging between 2-8 ns (Si substrate) and 3-11 ns (SiO2 substrate) for QDs up 10 nm in size.

Original languageEnglish (US)
Article number035122
JournalPhysical Review B
Volume96
Issue number3
DOIs
StatePublished - Jul 13 2017

Bibliographical note

Funding Information:
The authors acknowledge the financial support from the Brazilian National Research Council (CNPq) and CAPES foundation.

Publisher Copyright:
© 2017 American Physical Society.

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