One-dimensional effects in quantum wires made from a double heterojunctionbased on the AlAs GaAs system

Narrow quantum wires of length 1-4 mu m were fabricated by wet chemical etc hing from a heterostructure consisting of a 10 nm GaAs quantum well embedde d into a delta-doped AlAs/GaAs short-period superlattice. Studying the magn etotransport at T = 0.3 K the diffuse boundary scattering effect is observe d. The position of the occurring peak depends strongly on the top gate volt age in contrast to previous reports. The depopulation of magnetoelectric su bbands is identified in power spectra of the oscillatory magnetoresistance. The experimental results are used to estimate an electrical wire width and the Fermi wave vector. It is found that the wire conductance is mainly con trolled through a narrowing of the potential from the sides. This is attrib uted to the stronger Fermi level pinning in the barrier layer of a double h eterostructure compared to a single heterojunction. A wire of length 1 mu m shows conductance steps at zero field. They vanish on applying a weak magn etic field. (C) 1999 American Institute of Physics. [S0021-8979(99)00915-9] .