High transconductance in‐plane‐gated transistors

Focused‐ion‐beam written one‐dimensional field‐effect transistors are fabricated and characterized at room temperature. By writing these in‐plane‐gated channels with geometrical widths of 0.2–1.1 μm in heterostructures, we obtain one‐dimensional transconductances of up to 170 μS for two channels in parallel. We determine the effective width of the channels, which ranges between 790 nm and zero, being still reproducibly tunable at a few nanometers. The reproducibility in fabrication already of the prototypes presented here is sufficient for integration applications. We observe current densities, which can only be explained by a strong velocity overshoot of the electrons and promises excellent high‐frequency behavior of the device. The in‐plane‐gate transistor does not need any alignment and can easily be interconnected and integrated with a writing speed exceeding 106 devices per s.