Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors

We present a dielectric stack that does not significantly degrade FE, and demonstrate a high-frequency graphene device that utilizes this material

Damon B. Farmer; Hsin-Ying Chiu; Yu-Ming Lin; Keith A. Jenkins; Fengnian Xia; Phaedon Avouris

2009

Scholarcy highlights

  • Much of the interest surrounding graphene is due to the high carrier mobility that is exhibited by this material
  • This makes graphene a material of great promise as the active element in electronic devices, those based on low-noise and high-frequency operation
  • Much of this scattering is produced by the detrimental interaction between graphene and the gate dielectric material, a necessary component in top-gated field-effect transistors device architecture
  • We have been able to achieve graphene transistor operating frequencies in excess of 20 GHz, but this was done after topgate dielectric deposition caused an order of magnitude decrease in carrier mobility
  • Beyond changing the doping level, buffered dielectric processing has a minimal effect on the transfer characteristics. Both the minimum current value at VDirac and the maximum hole transconductance remain within 15% of their initial values
  • Methyl and hydroxyl groups contained within the polymer structure serve as ideal reaction sites for atomic layer deposition of HfO2, the high- component of the dielectric stack
  • We have shown that the addition of a low- polymer buffer layer between graphene and conventional gate dielectrics helps to minimize mobility degradation in top-gated graphene field-effect transistors. Possible reasons for this include the suppression of extrinsic surface phonons by the buffer layer and reduction of the impurity concentration due to inherent properties of the polymer

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