Phase Coherence Length in Planar Doped Thin GaAs Wires Fabricated by Ion Beam Etching

Abstract

Electrical transport properties have been studied in a film and wires fabricated from a monolayer doped or a homogeneously doped thin GaAs by mesa etching techniques. The dependence of the electron wave coherency upon the wire widths and fabrication processes is investigated from their low-temperature behavior of the phase coherence length Lφ derived from the nagative magnetoresistance and the amplitude of the conductance fluctuations. Low-temperature saturations of Lφ occur only in narrow wires. This suggests that Lφ is affected by the ion beam induced damage within the mesa side walls. A difference in Lφ between reactive ion-beam-etched and ion-milled wires is explained by the decrease of the diffusion constant. The corresponding difference in the conductance fluctuation amplitudes is larger than that expected from the difference in Lφ.