Local stiffness and work function variations of hexagonal boron nitride on Cu(111)

Area of Science:

• Surface science
• Nanotechnology
• Condensed matter physics

Background:

• Hexagonal boron nitride (h-BN) is a 2D material with unique electronic properties.
• h-BN on Cu(111) serves as a decoupling layer for heterostructures and a template for adsorbates.
• Understanding the nanoscale properties of h-BN/Cu(111) is crucial for advanced material applications.

Purpose of the Study:

• To simultaneously measure the electronic and mechanical properties of h-BN on Cu(111) at the nanoscale.
• To quantify work function variations and sheet stiffness of the h-BN/Cu(111) system.
• To investigate the corrugation and flatness of the h-BN layer on the Cu(111) substrate.

Main Methods:

• Combined scanning tunnelling and atomic force microscopy (STM/AFM) with a qPlus sensor.
• Measurement of work function variations using field emission resonance shifts and Kelvin probe force microscopy (KPFM).
• Analysis of 3D force profiles and constant force maps to determine mechanical properties and height profiles.

Main Results:

• Work function variations of approximately 100 meV were observed on the h-BN/Cu(111) superstructure.
• Sheet stiffness of the h-BN layer was determined to be 9.4 ± 0.9 N·m⁻¹, significantly higher than on Rh(111).
• A corrugation of 0.6 ± 0.2 Å was measured for the h-BN/Cu(111) system, clarifying its flatness.

Conclusions:

• The study successfully demonstrated the simultaneous measurement of electronic and mechanical properties of 2D materials.
• The results provide quantitative data on the work function, stiffness, and corrugation of h-BN/Cu(111).
• This work contributes to a better understanding of h-BN as a decoupling layer and template for nanoscale applications.