Low-force spectroscopy on graphene membranes by scanning tunneling microscopy. Issue 4 (12th January 2018)

• Record Type: Journal Article
• Authors: Uder, Bernd; Gao, Haibin; Kunnas, Peter; de Jonge, Niels; Hartmann, Uwe
• Is Part Of: Nanoscale. Volume 10:Issue 4(2018)
• Page Start: 2148
• Page End: 2153
• Publication Date: 2018-01-12
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c7nr07300c
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : The subtle interaction between a tip and an atomically thin graphene membrane in tunneling contact can be used for nonindenting force spectroscopy. This was applied to a freestanding single layer of graphene and permitted the detection of Young's modulus. Abstract : Two-dimensional atomically flat sheets with a high mechanical flexibility are very attractive as ultrathin membranes but are also inherently challenging for microscopic investigations. We report on a method using Scanning Tunneling Microscopy (STM) under ultra-high vacuum conditions for non-indenting low-force spectroscopy on micrometer-sized freestanding graphene membranes. The method is based on applying quasi-static voltage ramps with active feedback at low tunneling currents and ultimately relies on the attractive electrostatic force between the tip and the membrane. As a result a bulge-test scenario can be established. The convenience and simplicity of the method relies on the fact that the loading force and the membrane deflection detection are both provided simultaneously by the STM. This permits the continuous measurement of the stress–strain relation. Electrostatic forces applied are typically below 1 nN and the membrane deflection is detected at sub-nanometer resolution. Experiments on single-layer graphene membranes with a strain of 0.1% reveal a two-dimensional elastic modulus E 2D = 220 N m −1 .