Mohammad H Maneshian et al 2009 Nanotechnology 20 495703 doi:10.1088/0957-4484/20/49/495703
Mohammad H Maneshian1, Ming-Te Lin1, David Diercks2 and Nigel D Shepherd1,2,3
Show affiliationsTitanium was deposited onto silicon carbide (6H-SiC) using the 248 nm line of an excimer laser in a vacuum of 10−6 Torr, and ohmic contacts were formed by annealing the structure at ~1000 °C. Further anneals between 1350 and 1430 °C did not degrade the formed contacts, and Raman analysis confirmed that sublimation of silicon from the near surface layers of the silicon carbide between the contact pads resulted in graphene formation after 5 min, 1428 °C anneals. The graphene formation was accompanied by a significant enhancement of ohmic behavior, and, it was found to be sensitive to the temperature ramp-up rate and annealing time. High-resolution transmission electron microscopy showed that the interface between the metal and silicon carbide remained sharp and free of macroscopic defects even after 30 min, 1430 °C anneals. The interface was determined to be carbon rich by elemental analysis, which indicates metal carbide formation. The potential of this approach for achieving ohmic contacts and graphene formation on silicon carbide substrates is discussed. A mechanism for the sequential formation of ohmic contacts then graphene is proposed.
73.40.Ns Metal-nonmetal contacts
78.30.-j Infrared and Raman spectra
61.48.-c Structure of fullerenes and related hollow molecular clusters
68.37.Lp Transmission electron microscopy (TEM)
73.63.-b Electronic transport in nanoscale materials and structures
Condensed matter: electrical, magnetic and optical
Surfaces, interfaces and thin films
Issue 49 (9 December 2009)
Received 10 August 2009, in final form 2 October 2009
Published 6 November 2009
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