Determination of Cleavage Energy and Efficient Nanostructuring of Layered Materials by Atomic Force Microscopy

A method is presented to use atomic force microscopy to measure the cleavage energy of van der Waals materials and similar quasi-two-dimensional materials. The cleavage energy of graphite is measured to be 0.36 J/m², in good agreement with literature data. The same method yields a cleavage energy of 0.6 J/m² for MoS₂ as a representative of the dichalcogenides. In the case of the weak topological insulator Bi₁₄Rh₃I₉ no cleavage energy is obtained, although cleavage is successful with an adapted approach. The cleavage energies of these materials are evaluated by means of density-functional calculations and literature data. This further validates the presented method and sets an upper limit of about 0.7 J/m² to the cleavage energy that can be measured by the present setup. In addition, this method can be used as a tool for manipulating exfoliated flakes, prior to or after contacting, which may open a new route for the fabrication of nanostructures.