Extremely uniform epitaxial growth of graphene from sputtered SiC films on SiC substrates
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Extremely uniform epitaxial growth of graphene from sputtered SiC films on SiC substrates Fuminori Mitsuhashi1, Masaya Okada1, Yasunori Tateno2, Takashi Nakabayashi2, Masaki Ueno1, Hiroyuki Nagasawa3, Hirokazu Fukidome3 and Maki Suemitsu3 1 Semiconductor Technologies Laboratory, Sumitomo Electric Industries, Ltd., Koya-kita 1-1-1, Itami, Hyogo, Japan 2 Transmission Devices Laboratory, Sumitomo Electric Industries, Ltd., Taya 1, Sakae-ku, Yokohama, Kanagawa, Japan 3 Research Institute of Electrical Communication, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi, Japan ABSTRACT A novel method to fabricate uniform epitaxial graphene on C-face SiC substrates was investigated. Graphene was grown on the C-face 6H-SiC substrates with a sputtered SiC film by annealing temperatures ranging from 1400 to 1900 °C under an Ar ambient. The fractional area of the graphene having the layer number of two was about 95% in a 75×75 μm square by a Raman mapping and a low energy electron microscopy. Graphene on the C-face SiC fabricated by this method is quite uniform compared to that made by a conventional method without the sputtered SiC films and is thus suitable for high frequency analog devices. INTRODUCTION Graphene has an extremely high mobility around 200,000 cm2/Vs, much higher than that of known semiconductors, due to its anomalous two-dimensional carbon honeycomb structure [1-6]. It is therefore expected as an ideal material for high frequency analog devices in terahertz wireless communications. While there are several methods to fabricate graphene for electronic devices, the wellknown mechanical exfoliation and the chemical vapor deposition methods are both unsuitable due to the cost and the quality caused by the transferring process prerequisite to the methods. Epitaxial graphene (EG), which is fabricated by thermal decomposition of SiC substrates, attracts recent attentions as a candidate material for devices because it requires no transferring processes. Epitaxial graphene can be grown on both the SiC (000-1) (C-face) and the SiC (0001) (Si-face), with the former being superior in the carrier mobility over the latter. The epitaxial graphene on the SiC C-face, however, has a drawback in the on-wafer uniformity of the layer number distribution due to the high decomposition activity [7]. In this work, we developed a novel method to fabricate a uniform epitaxial graphene on the SiC C-face substrates by using a sputtered SiC film on the substrate. EXPERIMENT Graphene was grown on the C-face of semi-insulating 6H-SiC substrates with or without the sputtered SiC films. The SiC films were deposited by an RF magnetron sputtering with the several different thicknesses from 1 to 5 nm. The graphitization was conducted at temperatures
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ranging from 1400 to 1900 °C under an Ar ambient at 90 k
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