Quasi-free-standing monolayer and bilayer graphene growth on homoepitaxial on-axis 4H-SiC(0 0 0 1) layers |
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| Affiliation: | 1. Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden;2. Department of Microtechnology and Nanoscience, Microwave Electronics Lab, Chalmers University of Technology, Kemivägen, 41296 Göteborg, Sweden;1. Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada;2. Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada;1. National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom;2. Department of Physics, Chemistry and Biology, Linkoping University, S-58183 Linkoping, Sweden;1. Key Laboratory of Advanced Micro/Nano Functional Materials, Department of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China;2. National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, China;3. Energy-Saving Building Materials Innovative Collaboration Center of Henan Province, Xinyang Normal University, Xinyang 464000, China;4. Key Laboratory of Ecophysics and Department of Physics, College of Science, Shihezi University, Xinjiang 832003, China;1. College of Applied Science, Taiyuan University of Science and Technology, 030024 Taiyuan, China;2. Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and Hubei Nuclear Solid Physics Key Laboratory, Wuhan University, 430072 Wuhan, China;3. Texas Center for Superconductivity, University of Houston, Houston, TX, USA |
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| Abstract: | Quasi-free-standing monolayer and bilayer graphene is grown on homoepitaxial layers of 4H-SiC. The SiC epilayers themselves are grown on the Si-face of nominally on-axis semi-insulating substrates using a conventional SiC hot-wall chemical vapor deposition reactor. The epilayers were confirmed to consist entirely of the 4H polytype by low temperature photoluminescence. The doping of the SiC epilayers may be modified allowing for graphene to be grown on a conducing substrate. Graphene growth was performed via thermal decomposition of the surface of the SiC epilayers under Si background pressure in order to achieve control on thickness uniformity over large area. Monolayer and bilayer samples were prepared through the conversion of a carbon buffer layer and monolayer graphene respectively using hydrogen intercalation process. Micro-Raman and reflectance mappings confirmed predominantly quasi-free-standing monolayer and bilayer graphene on samples grown under optimized growth conditions. Measurements of the Hall properties of Van der Pauw structures fabricated on these layers show high charge carrier mobility (>2000 cm2/Vs) and low carrier density (<0.9 × 1013 cm?2) in quasi-free-standing bilayer samples relative to monolayer samples. Also, bilayers on homoepitaxial layers are found to be superior in quality compared to bilayers grown directly on SI substrates. |
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