Top gated graphene transistors with different gate insulators

Top gated graphene field effect transistors with AlN and Si 3 N 4 gate insulator materials were fabricated by plasma assisted deposition. Transistors with an AlN top gate insulator showed a reduced mobility and channel carrier density, whereas for the transistors with Si 3 N 4 dielectric an increase of the mobility and a decrease of the channel carrier density was observed. The reduced carrier density can be explained by bond formation between the insulator and the graphene sheets. The different behaviour of the carrier mobility is due to defect passivation by H 2 in case of Si 3 N 4 and defect formation in the graphene channel for the AlN gate insulator. A reduced transconductance in top gate device configurations compared to the back gate configurations was observed, which can be caused by the Klein paradox or differences in the trap densities in the top gate insulators. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)