We have fabricated and measured ballistic graphene transistors with twooblique gates that can be independently biased. The gate lengths are about 38nm and are separated by a distance of 30 nm, the tilting angle being of 45owith respect to source and drain electrodes distanced at 190 nm. Electricmeasurements reveal specific properties of ballistic carrier transport, i.e.nonlinear drain voltage-drain current dependence, showing a saturation region,and negative differential resistance at certain bias voltages, which cannot beexplained without physical mechanisms related to ballistic transport. Tens ofballistic transistors, with very large transconductances, were fabricated on achip cut from a 4 inch graphene wafer. Such double-gate transistorconfigurations can be used also as extremely efficient, state-of-the-artphotodetectors.
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