Abstract
Graphene was synthesized on SiO2/Si wafers as large as 200 mm in diameter by thermal chemical vapor deposition (CVD) using Fe or Cu films as catalyst, and top-gated field-effect transistors (FETs) were fabricated directly on the wafer using a graphene-transfer-free process. For transistor fabrication, graphene was synthesized on patterned Fe films. The iron was subsequently etched after both ends of the graphene were fixed by source and drain electrodes (Au/Ti), resulting in the graphene channels bridging the electrodes all over the wafer. Top-gated FETs were then formed after covering the channels with HfO2 by the atomic layer deposition (ALD) method. The fabricated transistors exhibit ambipolar behavior and can sustain a high-density current. Dependence of graphene growth on catalyst types and various growth parameters was also investigated.