Weak localization and spin‐orbit interaction in self‐organized In _0.2 Ga _0.8 As quantum wires on GaAs (221)A substrates

Abstract

Anisotropic negative magnetoresistance (MR) parallel and perpendicular to the wires in the regime of quantum interference of hole gas has been investigated in self-organized In 0.2 Ga 0.8 As quantum wires (QWRs) grown on GaAs (221)A substrates by MBE and separated from p-type Si-doped Al 0.35 Ga 0.75 As by an undoped spacer layer of it (thickness L s ) in order to address issues concerning the dimensionality in weak localization (WL) as well as spin-orbit (SO) interaction. For L s = 3 nm, the best fits of the parallel MR to the 2D WL theory have been obtained with τ so ~ 24 ps, being well described by the model of anisotropic 2D WL for strong lateral coupling of the wires. For L s = 20 nm, on the other hand, the best fits to 1D WL theory have been obtained with τ so ~ 150 ps assuming diffusive boundary scattering and the data cannot be fit to 2D WL, being well described by the model of quasi-1D WL. In addition, the data for L s = 10 nm show a featureof the crossover between 2D WL and 1D WL, indicating the intermediate lateral coupling between the wires.