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

Beilstein Journal of Nanotechnology, vol. 12, pp. 559–565

Abstract

Combined scanning tunnelling and atomic force microscopy using a qPlus sensor enables the measurement of electronic and mechanic properties of two-dimensional materials at the nanoscale. In this work, we study hexagonal boron nitride ( h -BN), an atomically thin 2D layer, that is van der Waals-coupled to a Cu(111) surface. The system is of interest as a decoupling layer for functional 2D heterostructures due to the preservation of the h -BN bandgap and as a template for atomic and molecular adsorbates owing to its local electronic trapping potential due to the in-plane electric field. We obtain work function (Φ) variations on the h -BN/Cu(111) superstructure of the order of 100 meV using two independent methods, namely the shift of field emission resonances and the contact potential difference measured by Kelvin probe force microscopy. Using 3D force profiles of the same area we determine the relative stiffness of the Moiré region allowing us to analyse both electronic and mechanical properties of the 2D layer simultaneously. We obtain a sheet stiffness of 9.4 ± 0.9 N·m −1 , which is one order of magnitude higher than the one obtained for h -BN/Rh(111). Using constant force maps we are able to derive height profiles of h -BN/Cu(111) showing that the system has a corrugation of 0.6 ± 0.2 Å, which helps to demystify the discussion around the flatness of the h -BN/Cu(111) substrate.

Authors 5

1. Abhishek Grewal

   Max Planck Institute for Solid State Research

   Affiliation as printed

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany,

2. Yuqi Wang

   Forschungszentrum Jülich · Max Planck Institute for Solid State Research

   Affiliation as printed

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

   Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany,

   Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany,

3. Matthias Münks

   Max Planck Institute for Solid State Research

   Affiliation as printed

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany,

4. Klaus Kern

   Max Planck Institute for Solid State Research · École Polytechnique Fédérale de Lausanne

   Affiliation as printed

   Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

   Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland and

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany,

5. Markus Ternes Aachen II. Institute of Physics

   Forschungszentrum Jülich · Max Planck Institute for Solid State Research · RWTH Aachen University

   Affiliation as printed

   II. Institute of Physics, RWTH Aachen University, D-52074 Aachen, Germany

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

   Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany

   Max Planck Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany,

   Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany,