Back-gated split-gate transistor: A one-dimensional ballistic channel with variable Fermi energy

Abstract

We have studied the quantized conductance of a one-dimensional ballistic channel in the two-dimensional electron gas of a back-gated GaAs/AlGaAs heterostructure. A standard Schottky split-gate fabricated with electron-beam lithography techniques is used to define the one-dimensional channel, but we incorporate an epitaxially grown in situ back-gate, situated ∼1 μm below the electron gas, to provide additional control of the carrier density. Quantized conductance steps can be induced by changing the bias on either gate, highlighting the self-consistent nature of the electrostatics involved. We show that we can, in principle, achieve independent control of the one-dimensional carrier density and channel width.