Vishal Panchal1, Héctor Corte-León1,2, David M. A. Mackenzie3, Olga Kazakova1 and Dirch H. Petersen3 1. National Physical Laboratory, Teddington, TW11 0LW, United Kingdom 2. Royal Holloway, University of London, Egham, Surrey, TW20 0EX, United Kingdom 3. Center for Nanostructured Graphene, Technical University of Denmark, Lyngby, 2800 Kgs, Denmark ![]() We present local electric field sensitivity maps of Hall cross devices of 1-2LG imaged using electrical scanning gate microscopy (SGM). These experimental results are compared to theoretical maps obtained from equivalent finite element simulations for qualitative comparison. Using both these techniques, we observe abrupt inversion in the voltage response of the device when locally gating 2LG islands compared to 1LG. These manifests from differences in charge neutrality point of 1-2LG, and the ability of the SGM tip bias to manipulate the carrier density and mobility. We further derive an analytical model to extract directly the carrier type and sheet carrier density from SGM measurements. With this we observe carrier type inversion between 1LG and 2LG. Thus, we demonstrate that SGM is an effective tool for studying gating effects in graphene devices with 10's of nm scale spatial resolution. Moreover, these results prove that strategical device design with specific 2LG structures can be used to enhance sensitivity of devices to electric fields. 1. T. Yager et al., Nano Letters, 13, 9, 4217-4223 (2013) 2. V. Panchal et al., 2D Materials, 3, 1, 15006 (2016) ![]() Vishal's current scientific interests include nano- and micro-scale studies on graphene and other related 2D materials. His expertise are in local electrical and optical characterizations with functional scanning probe microscopy techniques such as Kelvin probe force microscopy, conductive atomic force microscopy, scanning gate microscopy, scattering scanning near-field optical microscopy, etc. |