Excitons in atomically thin black phosphorus

TL;DR

This study investigates the optical properties of single-layer black phosphorus, revealing excitonic effects, substrate-dependent emission energies, and temperature-induced band gap shifts through combined Raman and photoluminescence spectroscopy.

Contribution

It provides experimental evidence of excitonic effects and substrate influence in single-layer black phosphorus using in situ spectroscopy techniques.

Findings

Demonstrates single-layer character via Raman spectroscopy

Shows substrate-dependent emission energies due to dielectric screening

Describes temperature-induced blue shift of emission with a two oscillator model

Abstract

Raman scattering and photoluminescence spectroscopy are used to investigate the optical properties of single layer black phosphorus obtained by mechanical exfoliation of bulk crystals under an argon atmosphere. The Raman spectroscopy, performed in situ on the same flake as the photoluminescence measurements, demonstrates the single layer character of the investigated samples. The emission spectra, dominated by excitonic effects, display the expected in plane anisotropy. The emission energy depends on the type of substrate on which the flake is placed due to the different dielectric screening. Finally, the blue shift of the emission with increasing temperature is well described using a two oscillator model for the temperature dependence of the band gap.