Fabrication and Characterization of Graphene Field Effect Transistors

Abstract: Exceptional electronic properties of graphene have attracted the attention of solid-state physicists and more recently device engineers. From electronic device point of view, graphene is a promising material for future smaller and faster electronics, and it demands extensive amount of research. In this work, graphene is used as the channel material in field effect transistors (FETs). First KTH’s back-gate and top-gate graphene FETs (GFETs) were fabricated using exfoliated graphene on 90 nm thick silicon dioxide films on silicon substrates. Aluminum Oxide (Al2O3) high-K gate insulator was deposited by atomic layer deposition (ALD). Back-gate transfer characteristics of uncovered devices show current modulation with hysteresis and a charge neutrality point about +5 V. After 20 nm thick Al2O3 film deposition, hysteresis is effectively suppressed, and the charge neutrality point moves toward negative gate voltages of about -14 V. Furthermore, the mobility is just degraded by a factor of two after high-k deposition process. The electrical characterization confirmed the effectiveness of the fabrication and reveals the importance of contact optimization for device performance and mobility extraction.