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

• Published in: Journal of applied physics 2012-01, Vol.111 (1), p.013716-013716-6
• Main Authors: Shen, T., Neal, A. T., Bolen, M. L., Gu, J. J., Engel, L. W., Capano, M. A., Ye, P. D.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3675464

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 >10K, the transition width goes as T − κ with exponent k ∼0.42. This universal scaling exponent agrees well with those found in III−V heterojunctions with short-range alloy disorders and in exfoliated graphene.