Structure of χ₃-Borophene Studied by Total-Reflection High-Energy Positron Diffraction (TRHEPD)

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Borophene, a monolayer of boron atoms, is a novel material with tunable electronic properties.
• Understanding the structural characteristics of borophene polymorphs on substrates is crucial for its applications.

Purpose of the Study:

• To determine the precise atomic structure of the χ3-borophene phase on a silver (Ag(111)) surface.
• To investigate the interaction between χ3-borophene and the Ag(111) substrate.

Main Methods:

• Total-reflection high-energy positron diffraction (TRHEPD) was employed to probe the surface structure.
• Dynamical diffraction theory was used to compare experimental data with theoretical models.
• Results were corroborated with X-ray standing wave-excited X-ray photoelectron spectroscopy (XSW-XPS).

Main Results:

• The χ3-borophene layer on Ag(111) adopts a flat structure.
• The distance between the borophene layer and the topmost silver layer was determined to be 2.4 Å.
• The in-plane atomic arrangement of χ3-borophene aligns with theoretical predictions.

Conclusions:

• χ3-borophene on Ag(111) is a structurally stable, flat monolayer.
• The weak interaction with the substrate classifies χ3-borophene among epitaxial 2D materials like graphene.
• These findings pave the way for exploring borophene-based electronic devices.