We found that an extremely thin resist pattern on silicon dioxide can be directly transformed into a graphene field effect transistor (FET) channel via interfacial graphitization of liquid gallium. These patterned graphene FETs have p-type characteristics and a maximum conductance modulation of 22% against an applied gate voltage that ranges from -50 to +50 V at room temperature. Further reduction of the initial resist thickness improves the modulation ratio remarkably up to more than 100%, but at the same time the conductance deteriorates greatly, to less than 10(-9) S. We believe that electron scattering at the grain-domain boundaries strongly increases the resistance of the channel, leading to an apparent on-off ratio increase as if the channel was behaving as a semiconductor. (C) 2011 Elsevier B.V. All rights reserved.