Qualitative analysis of scanning gate microscopy on epitaxial graphene

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • David Mackenzie

  • Vishal Panchal
  • Hector Corte-Leon
  • Dirch H. Petersen
  • Olga Kazakova

Research units

  • Technical University of Denmark
  • National Physical Laboratory

Abstract

We present scanning gate microscopy (SGM) studies of graphene Hall-cross devices where bi-layer graphene (2LG) regions show unexpected signal inversion relative to single-layer graphene (1LG), an observation reproduced via finite element modelling of the current densities. This is attributed to gate-induced charge carrier redistribution between the two layers in 2LG. Hall cross devices were fabricated from epitaxial graphene 6H-SiC(0001) and were covered by 1LG/2LG with the area ratio of 85: 15%, respectively. Local electric-field sensitivity maps of the devices were obtained in two different measurement geometries using electrical SGM with a conductive tip, where it was observed that the voltage of 2LG islands was inverted relative to anticipated reference maps. Finite element modelling of the current densities and voltage response showed good qualitative agreement with the SGM maps when the effect of the gate was reversed for 2LG. The behaviour is attributed to gate-induced charge carrier redistribution between the two layers in 2LG. The model can be used generally as a tool to predict mixed 1LG/2LG response to electric field. Moreover, regions near the corners of the device show the highest sensitivity when the local electric field was applied to the scanning probe microscopy tip. These regions are capable of detecting highly local electric fields down to 110 kV cm(-1).

Details

Original languageEnglish
Article number025023
Number of pages10
Journal2D Materials
Volume6
Issue number2
Publication statusPublished - 28 Feb 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • scanning gate microscopy, epitaxial graphene, finite element simulations, KPFM, electric field effect, electrical sensitivity, ELECTRONIC-PROPERTIES, BILAYER GRAPHENE, SUBSTRATE, BANDGAP, SURFACE

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