TRANSPORT IN NOVEL GATED QUANTUM WIRES - THE IMPACT OF WIRE LENGTH

Split-gate quantum wires of various lengths including 0.0-mu-m (constrictions), 0.5-mu-m, and 1.0-mu-m have been fabricated on an AlGaAs/GaAs modulation-doped heterostructure. Confinement is achieved using a split-gate formed by two 40 nm Au/Pd lines, resulting in small gate leakage and short electron-beam writing times. In a two-probe measurement, we have observed strong conductance steps at 4.2 K in 0.5- mu-m long split-gate quantum wires. These features, which are characteristic of near ballistic electron transport through the wire, are present at temperatures as high as 10 K. Transport through the 0.0- mu-m constriction was dominated by tunneling and transport in the 1.0- mu-m long wires was of a diffusive nature.