Synthesis of Few-Layer and Multi-Layer Graphene and Fabrication of Top-Gated Field Effect Transistors without Using Transferring Processes

We have fabricated top-gated field effect transistors (FETs) using graphene synthesized by chemical vapor deposition directly on a SiO2/Si substrate without using any transferring processes. Graphene was synthesized on an Fe catalyst film on the substrate at 650°C. The catalyst film was then etched after both ends of the graphene were fixed by source and drain electrodes, leaving the graphene channel connecting the two electrodes. Top-gated FETs were then made by covering graphene channels with HfO2 and depositing top electrodes. The drain current was successfully modulated by the gate voltage and exhibited the bipolar behavior that is characteristic of graphene. Also, it has been shown that graphene channels can sustain an electric current with a density of 107–108 /cm2. Our newly developed fabrication process paves a way to fabricate graphene transistors all over large substrates including Si and glass.