Graphene field-effect transistors are fabricated using CVD-grown graphene and a wet transfer technique. Devices are characterized in terms of carrier mobility, contact resistance, output and transfer characteristics. We found that the mobility decreases and contact resistance increases with the decreasing graphene microstrip width. In addition, we found that graphene FET characteristics strongly ... [Show full abstract] depend on annealing time. The behavior of device characteristics is explained by discussing carrier scattering on defects and impurities, and the formation of pn-junctions in graphene.