SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Graphene I: Adsorption, Intercalation and Doping
O 82.7: Vortrag
Donnerstag, 30. März 2023, 16:30–16:45, GER 37
Tailoring permanent carrier density in epitaxial graphene by F4-TCNQ molecular doping for quantum Hall resistance standards — •Yefei Yin, Atasi Chatterjee, Davood Momeni, Mattias Kruskopf, Martin Götz, Stefan Wundrack, Frank Hohls, Klaus Pierz, and Hans Werner Schumacher — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
A prerequisite for the development of graphene electronics is the reliable control of its carrier density. Since epi-graphene on SiC already exhibits a high electron density of up 1013 cm−2, the goal is a controlled reduction towards the charge-neutrality point. This was achieved by molecular doping with the acceptor F4-TCNQ doping stacks deposited on graphene. By precise adjustment of the dopant concentration and controlling the initial carrier density of the undoped graphene, we can tune the carrier density in a wide range from intrinsic n- to the p-type. Precision measurements of the quantum Hall resistance show a quantization accuracy of 10−9 which underlines the high quality and suitability of this doping method for electronic device application in metrology. [1] Our data show a correlation between the electron density and the onset of the i = 2 quantum Hall plateau which gives a valuable criterion for evaluating graphene-based resistance standards since the *classical* relation (n = ieB/h) to determine the centre of the quantum Hall plateau is not valid in epi-graphene. The results are discussed in the charge transfer model. [1] Y.Yin et al., Adv. Physics Res. 2022, DOI: 10.1002/apxr.202200015.