Electronic properties of black phosphorus using monochromated low-loss EELS

In the present study, monochromated low-loss electron energy-loss spectroscopy in a scanning transmission electron microscope, confronted with ab-initio calculations, is used to investigate the bandgap and excitons energies of black phosphorus flakes in the near infrared region. Due to the monochromation of the electron beam and to a spectrometer with an energy resolution of 20 meV, a direct measurement of the narrow bandgap energy, E-0, of about 0.33 eV was successful, along with an intraband electronic transition E-1 at around 0.75 eV. Interestingly, additional transitions, excitonic in nature, are identified at 0.42 eV and 0.55 eV, the intensity of which increases with decreasing thickness. All these findings demonstrate the ability of monochromated low-loss electron energy loss spectroscopy to reveal unprecedented electronic and excitonic transitions in very narrow bandgap semiconductors.

Automated summary

This study utilizes monochromated low-loss electron energy-loss spectroscopy to investigate the bandgap and exciton energies of black phosphorus flakes in the near infrared region. The research successfully demonstrates the ability of this technique to reveal unprecedented electronic and excitonic transitions in very narrow bandgap semiconductors.