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arXiv · 1112.4345

Quantum-Hall plateau-plateau transition in top-gated epitaxial graphene grown on SiC (0001)

Tian Shen·Adam T. Neal·Michael L. Bolen·Jiangjiang Gu·Lloyd W. Engel·Michael A. Capano·Peide Ye
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Abstract

We investigate the low-temperature magneto-transport properties of monolayer epitaxial graphene films formed on the Si-face of semi-insulating 4H-SiC substrates by a high temperature sublimation process. A high-k top-gate on the epitaxial graphene is realized by inserting a fully oxidized nanometer thin aluminum film as a seeding layer, followed by an atomic layer deposition process. At low temperatures, the devices demonstrate a strong field effect by the top gate with an on/off ratio of ~7 and an electron mobility up to ~3250 cm^2/Vs. After the observation of the half-integer quantum Hall effect for monolayer epitaxial graphene films, detailed magneto-transport measurements have been carried out including varying densities, temperatures, magnetic fields and currents. We study the width of the distinguishable quantum-Hall plateau to plateau transition (Landau level index n=0 to n=1) as temperature (T) and current are varied. For both gate voltage and magnetic field sweeps and T>10 K the transition width goes as T^{-\kappa} with exponent \kappa ~0.42. This universal scaling exponent agrees well with those found in III-V heterojunctions with short range alloy disorders and in exfoliated graphene.

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Tian Shen, Adam T. Neal, Michael L. Bolen, Jiangjiang Gu, Lloyd W. Engel, Michael A. Capano, Peide Ye. 2011-12-19. Quantum-Hall plateau-plateau transition in top-gated epitaxial graphene grown on SiC (0001). https://doi.org/10.1063/1.3675464

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