Layer-Dependent Pressure Effect on the Electronic Structure of 2D Black Phosphorus

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Few-layer black phosphorus (BP) is a promising two-dimensional material with tunable electronic properties.
• Understanding the impact of external stimuli like pressure on BP's electronic structure is crucial for device applications.

Purpose of the Study:

• To systematically investigate the pressure effects on the electronic structures of few-layer black phosphorus (BP).
• To analyze the layer-dependent behavior of pressure-induced shifts in optical transitions.
• To provide a theoretical framework for understanding these pressure-dependent phenomena.

Main Methods:

• Infrared spectroscopy was employed to study few-layer black phosphorus (BP) samples with layer numbers from 2 to 13.
• A tight-binding model incorporating a Morse potential for interlayer coupling was used for theoretical analysis.

Main Results:

• The pressure-induced shift of optical transitions in BP shows a strong dependence on the number of layers.
• Unlike bulk black phosphorus, the band gap of 2-layer BP increases with pressure up to 2 GPa.
• The pressure-induced shifts vary for different optical transitions within the same layer number.

Conclusions:

• The layer- and transition-index-dependent pressure effects in few-layer BP can be accurately explained by the developed theoretical model.
• This research offers insights for the rational design and engineering of van der Waals heterostructures based on black phosphorus.