dc and high-frequency transport in quasi-one-dimensional quantum wires with rough boundaries

We fabricate quasi-one-dimensional electron wires by low-energy ion-beam exposure in ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterojunctions and study their transport properties in the low- and high-frequency domain. Typical widths of our electron wires range from 100 nm to 1 μm. The static and far-infrared (FIR) conductivities are measured at low temperatures (T≤4.2 K) and high magnetic fields (B≤12 T). The experiments demonstrate that in these wires a large proportion of the boundary scattering events is diffuse. The FIR conductivity exhibits intersubband and intrasubband plasmon resonances. The linewidths of these excitations reflect an intriguing anisotropy that arises from a mode-dependent sensitivity of these high-frequency excitations on the boundary roughness. Photoluminescence experiments indicate that the confinement is accompanied by creation of defects in the plane of the electron system that strongly reduce the mobility of the electrons in the areas exposed to the ion beam.