Anisotropic exciton Stark shift in black phosphorus

TL;DR

This paper investigates how an in-plane electric field affects excitons in black phosphorus, revealing anisotropic polarizability and Stark shifts through direct Hamiltonian diagonalization.

Contribution

It provides the first detailed calculation of anisotropic excitonic Stark effects in black phosphorus, including excited states and high-field regimes.

Findings

Exciton polarizability is direction-dependent due to anisotropy.

The Stark effect persists at high electric fields, including ionization thresholds.

Anisotropic excitonic responses are characterized in detail.

Abstract

We calculate the excitonic spectrum of few-layer black phosphorus by direct diagonalization of the effective mass Hamiltonian in the presence of an applied in-plane electric field. The strong attractive interaction between electrons and holes in this system allows one to investigate the Stark effect up to very high ionizing fields, including also the excited states. Our results show that the band anisotropy in black phosphorus becomes evident in the direction dependent field induced polarizability of the exciton.