Electronic Structure of Few-Layer Black Phosphorus from μ-ARPES

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanoscience

Background:

• Black phosphorus (BP) is a 2D semiconductor with high charge carrier mobility and a tunable direct band gap.
• The electronic band structure of ultrathin BP has been challenging to access experimentally.
• Understanding the quasiparticle band structure is crucial for exploring BP's electronic properties.

Purpose of the Study:

• To experimentally determine the quasiparticle band structure of 2-9 layer black phosphorus.
• To investigate the electronic properties of ultrathin BP using advanced spectroscopic techniques.
• To provide experimental data for theoretical models of BP electronic structure.

Main Methods:

• Utilized a laser-based microfocus angle-resolved photoemission (μ-ARPES) system.
• Performed experimental measurements on few-layer (2-9 layers) black phosphorus samples.
• Analyzed the obtained photoemission spectra to extract electronic structure information.

Main Results:

• Successfully established the electronic structure of ultrathin BP from experiment.
• Observed ladders of anisotropic, quantized subbands with unique energy scaling.
• Quantified the anisotropy of effective masses and determined universal tight-binding parameters.

Conclusions:

• The experimental results provide unprecedented access to the electronic structure of ultrathin BP.
• The findings reveal deviations from conventional semiconductor quantum well behavior.
• The determined tight-binding parameters accurately describe the electronic structure across various thicknesses.