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HL: Fachverband Halbleiterphysik

HL 30: Poster I

HL 30.22: Poster

Dienstag, 17. März 2020, 13:30–15:45, P3

Back-gated FET operation in 4H SiC for controlling transport in epitaxial graphene nanojunctions — •Maria T. Schlecht, Christian Ott, Stefan Malzer, and Heiko B. Weber — Lehrstuhl für Angewandte Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany

For many experiments with epitaxial graphene on Silicon carbide (SiC) it is essential to leave graphene accessible, therefore charge carrier control must be achieved by a backgate buried in the substrate. This can be realized by placing an implanted conductive layer in the substrate without losing its semi-insulating behaviour. This has been successfully established on 6H SiC due to the vanadium compensation of the semi-insulating material [1]. Implanting a working back-gate within the technologically more relevant polytype 4H SiC is more challenging as it is "intrinsically" semi-insulating. Here, we present a study on implanted bottom gates for quasi-freestanding bilayer graphene (QFBLG) on 4H SiC using nitrogen as a dopant. Investigating various implantation profiles we found an optimum at an implantation concentration of 5·10¹⁷ cm⁻³ and a depth of 1 µm. A reduction of the charge carrier concentration by 5·10¹² cm⁻² at a gate voltage of 90 V was achieved. The back gate was proven to be working in the temperature range of interest from 30 K to 300 K and was only limited by leakage current. A local maximum of the leakage current at 120 K will be discussed taking into account defect levels within the SiC.[1] Waldmann et al, DOI: 10.1038/nmat2988 (2011)