Conductance Fluctuations in GaAs/AlGaAs Narrow Wires in Quasi-Ballistic Regime

Conductance Fluctuations due to the quantum interference of electrons have been studied in GaAs/AlGaAs narrow wires in the quasi-ballistic transport regime. Narrow channels of length 2 µm and 6 µm were confined by metallic split gates formed by electron beam lithography and a lift off technique. In the shorter wire, the amplitude of the fluctuations first increased as a function of increasing width, and finally approached to the constant value of e2/h. On the other hand, it was almost independent on channel width in the longer wire, as expected for the universal conductance mechanism in the diffusive transport regime. We suspect that the non universal width dependence in the shorter wire might result from averaging among the individual transmission channels, caused by the small number of scattering events.