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

Beilstein Journal of Nanotechnology

article

Abhishek Grewal¹  Yuqi Wang¹  Matthias Münks¹  Klaus Kern¹  Markus Ternes¹ 

[1] Max Planck Institut für Festkörperforschung;Peter Grünberg Institute;Institut de Physique;II. Institute of Physics, RWTH Aachen University

关键词: decoupling layers;    hexagonal boron nitride;    local stiffness;    Moirésuperstructure;    work function variation;   

DOI  :  10.3762/bjnano.12.46

学科分类：环境监测和分析

来源: Beilstein - Institut zur Foerderung der Chemischen Wissenschaften

【 摘 要 】

Combined scanning tunnelling and atomic force microscopy using a qPlus sensor enables the measurement of electronic andmechanic properties of two-dimensional materials at the nanoscale. In this work, we study hexagonal boron nitride (h-BN), anatomically thin 2D layer, that is van der Waals-coupled to a Cu(111) surface. The system is of interest as a decoupling layer forfunctional 2D heterostructures due to the preservation of the h-BN bandgap and as a template for atomic and molecular adsorbatesowing to its local electronic trapping potential due to the in-plane electric field. We obtain work function (Φ) variations on theh-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 areawe determine the relative stiffness of the Moiré region allowing us to analyse both electronic and mechanical properties of the 2Dlayer simultaneously. We obtain a sheet stiffness of 9.4 ± 0.9 N·m−1, which is one order of magnitude higher than the one obtainedfor 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 acorrugation of 0.6 ± 0.2 Å, which helps to demystify the discussion around the flatness of the h-BN/Cu(111) substrate.

【 授权许可】

CC BY