Structural and electrical characterization of ohmic contacts to graphitized silicon carbide

Titanium 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 approximately 1000 degrees C. Further anneals between 1350 and 1430 degrees C did not degrade the formed contacts, a...

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Bibliographic Details
Published in:Nanotechnology 2009-12, Vol.20 (49), p.495703-495703
Main Authors: Maneshian, Mohammad H, Lin, Ming-Te, Diercks, David, Shepherd, Nigel D
Format: Article
Language:English
Subjects:
Annealing
Carbon
Contact resistance
Defect annealing
Excimer lasers
Graphene
Ohmic
Silicon carbide
Titanium
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Summary:Titanium 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 approximately 1000 degrees C. Further anneals between 1350 and 1430 degrees 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 degrees 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 degrees 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.
ISSN:0957-4484
1361-6528
DOI:10.1088/0957-4484/20/49/495703