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HL: Fachverband Halbleiterphysik
HL 21: Graphene: Electronic Structure and Excitations (joint session O/HL)
HL 21.1: Vortrag
Dienstag, 18. März 2025, 10:30–10:45, H6
Doping of epitaxial graphene by proximitized 2D quantum islands — •Julian Koch1, Sergii Sologub1,2, Chitran Ghosal1, Dorothee Boesler1, and Christoph Tegenkamp1 — 1Institut für Physik, TU Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz — 2Institute of Physics, NAS of Ukraine, Nauki avenue 46, 03028 Kyiv
The effects of 2D quantum islands on the transport properties of monolayer graphene/SiC(0001) were investigated by magnetotransport. Two types of adsorbates are compared, Bi(110) and Pb(111) islands with average coverages of up to 3.6 bilayers (BL) and 3 monolayers (ML), respectively. The analysis is supported by structural investigations using SPA-LEED and STM. The doping behaviour of both materials is fundamentally different. In the case of Bi, the carrier concentration determined from the SdH oscillations remains at 1 × 1013 cm−2 independent of the Bi coverage, although photoemission spectroscopy revealed a strong doping of the graphene by Bi [1]. This strongly indicates a highly anisotropic carrier concentration across the surface and is confirmed by a positive, temperature independent contribution to the magnetoresistivity. The Bi islands rather behave as antidots and reduce the charge carrier mobility slightly from around 2250 cm2/(Vs) for MLG to 1920 cm2/(Vs) at 2.4 BL Bi. In contrast, there are no signs of an anisotropic carrier concentration or mobility when Pb is adsorbed. The electron concentration increases uniformly by approximately 5×1011 ML−1cm−2. The mobility is reduced from around 1400 cm2/(Vs) for MLG to 1200 cm2/(Vs) at 3 ML Pb.
[1] Gierz et al. Nano Lett. 8, 12, 4603 (2008)
Keywords: transport; magnetotransport; Hall effect; graphene; doping