Quantum wire FETs in δ-doped GaAs

We have used in-plane gates to produce quantum wire FETs from δ - doped GaAs. Two side gates are separated from a narrow channel by trenches patterned by electron beam lithography and reactive ion etching with BCl₃. Applying a reverse bias to the gates increases the resistivity of the wire which pinches off at voltages below -7 Volts. The large electron density in the wire drastically reduces the surface depletion and as a result the electrical width at zero gate bias corresponds to the structural width. The wires are characterised in terms of width, electron density and phase coherence length by means of low temperature magnetotransport measurements. The pinch-off characteristics and depletion mechanism are also discussed.