Nonlinear electron transport in quantum wires

Nonlinear electron transport in normally pinched-off quantum wires was stud ied. The wires were fabricated from AlGaAs/GaAs heterostructures with high- mobility two-dimensional electron gas by electron beam lithography and foll owing wet etching. At certain critical source-drain voltage the samples exh ibited a step rise of the conductance. The differential conductance of the open wires was noticeably lower than e(2)/h as far as only part of the sour ce-drain voltage dropped between source contact and saddle-point of the pot ential relief along the wire. The latter limited the electron flow injected to the wire. At high enough source-drain voltages the decrease of the diff erential conductance due to the real space transfer of electrons from the w ire in GaAs to the doped AlGaAs layer was found. In this regime the sign of differential magnetoconductance was changed with reversing the direction o f the current in the wire or the magnetic field, when the magnetic field li es in the heterostructure plane and is directed perpendicular to the curren t. The dependence of the differential conductance on the magnetic field and its direction indicated that the real space transfer events were mainly me diated by the interface scattering.