  Three types of first generation epitaxial graphene field effect transistors
(FET) are presented and their relative merits are discussed. Graphene is
epitaxially grown on both the carbon and silicon faces of hexagonal silicon
carbide and patterned with electron beam lithography. The channels have a Hall
bar geometry to facilitate magnetoresistance measurements. FETs patterned on
the Si-face exhibit off-to-on channel resistance ratios that exceed 30. C-face
FETs have lower off-to-on resistance ratios, but their mobilities (up to 5000
cm2/Vs) are much larger than that for Si-face transistors. Initial
investigations into all-graphene side gate FET structures are promising.
