Charge-density depinning at metal contacts of graphene field-effect transistors

Abstract

An anomalous distortion is often observed in the transfer characteristics of graphene field-effect transistors. We fabricate graphene transistors with ferromagnetic metal electrodes, which reproducibly display distorted transfer characteristics, and show that the distortion is caused by metal-graphene contacts with no charge-density pinning effect. The pinning effect, where the gate voltage cannot tune the charge density of graphene at the metal electrodes, has been experimentally observed; however, a pinning-free interface is achieved with easily-oxidizable metals. The distortion should be a serious problem for flexible electronic devices with graphene.

arXiv commentTo be published in Appl. Phys. Lett

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• Towards wafer scale fabrication of graphene based spin valve devices
• Electrically Controlled Adsorption of Oxygen in Bilayer Graphene Devices
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• Role of MgO barriers for spin and charge transport in Co/MgO/graphene non-local spin-valve devices
• Charge transfer and trapping as origin of a double dip in the transfer characteristics of graphene based field-effect transistors
• Non-linear spin Seebeck effect due to spin-charge interaction in graphene
• Direct electronic measurement of Peltier cooling and heating in graphene
• Photo-oxidation of Graphene in the Presence of Water
• Suppression of contact-induced spin dephasing in graphene/MgO/Co spin-valve devices by successive oxygen treatments
• Electronic Spin Transport in Dual-Gated Bilayer Graphene
• Determination of Carrier Type Doped from Metal Contacts to Graphene by Channel-Length-Dependent Shift of Charge Neutrality Points
• Observation of Negative Contact Resistances in Graphene Field-Effect Transistors
• Charge transport through graphene junctions with wetting metal leads
• Influence of Metal-Graphene Contact on the Operation and Scalability of Graphene Field-Effect-Transistors
• Carrier density modulation in graphene underneath Ni electrode
• Electron-hole asymmetry in two-terminal graphene devices
• Spin and charge transport in graphene-based spin transport devices with Co/MgO spin injection and spin detection electrodes
• Competitive interfacial charge transfer to graphene from the electrode contacts and surface adsorbates
• Path of the current flow at the metal contacts of graphene field-effect transistors with distorted transfer characteristics
• Reversible doping of graphene field effect transistors by molecular hydrogen: the role of the metal/graphene interface
• Experimental signature of bandgap opening in bilayer graphene at metal contacts
• Observation of quantum Hall plateau-plateau transition and scaling behavior of the zeroth Landau level in graphene p-n-p junctions