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Lookup NU author(s): Dr Enrique Escobedo-Cousin, Dr Konstantin VasilevskiyORCiD, Dr Toby Hopf, Professor Nick Wright, Professor Anthony O'Neill, Dr Alton Horsfall, Professor Jon Goss, Professor Peter Cumpson
Patterned few-layer graphene (FLG) films were obtained by local solid phase growth from nickel silicide supersaturated with carbon, following a fabrication scheme, which allows the formation of self-aligned ohmic contacts on FLG and is compatible with conventional SiC device processing methods. The process was realised by the deposition and patterning of thin Ni films on semi-insulating 6H-SiC wafers followed by annealing and the selective removal of the resulting nickel silicide by wet chemistry. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to confirm both the formation and subsequent removal of nickel silicide. The impact of process parameters such as the thickness of the initial Ni layer, annealing temperature, and cooling rates on the FLG films was assessed by Raman spectroscopy, XPS, and atomic force microscopy. The thickness of the final FLG film estimated from the Raman spectra varied from 1 to 4 monolayers for initial Ni layers between 3 and 20 nm thick. Self-aligned contacts were formed on these patterned films by contact photolithography and wet etching of nickel silicide, which enabled the fabrication of test structures to measure the carrier concentration and mobility in the FLG films. A simple model of diffusion-driven solid phase chemical reaction was used to explain formation of the FLG film at the interface between nickel silicide and silicon carbide.
Author(s): Escobedo-Cousin E, Vassilevski K, Hopf T, Wright N, O'Neill A, Horsfall A, Goss J, Cumpson PJ
Publication type: Article
Publication status: Published
Journal: Journal of Applied Physics
Year: 2013
Volume: 113
Issue: 11
Print publication date: 20/03/2013
Date deposited: 08/05/2013
ISSN (print): 0021-8979
ISSN (electronic): 1089-7550
Publisher: American Institute of Physics
URL: http://dx.doi.org/10.1063/1.4795501
DOI: 10.1063/1.4795501
Notes: Article no. 114309 is 11 pp.
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