M. Tornow et al., MAGNETOTRANSPORT PHENOMENA IN SINGLE ALGAAS GAAS QUANTUM WIRES GROWN ON LATERALLY PATTERNED SUBSTRATES/, Solid-state electronics, 40(1-8), 1996, pp. 323-328
Single, sub-micrometer wide quantum wires have been fabricated using m
olecular beam epitaxy on mesa-etched GaAs substrates, where the GaAs w
ire is embedded in AlGaAs. By using a Hall bar pattern, potential prob
es were directly attached to the wires while grown. To avoid problems
associated with anisotropic etching and regrowth, the wire structures
were oriented along the [100] crystallographic directions. From this f
abrication technique, described in detail by Shitara et al., Appl. Phy
s. Lett. 66, 2385 (1995), one can expect the formation of high quality
''self-aligned'' quantum wires with a confinement potential determine
d by the conduction band discontinuity of AlGaAs and GaAs, Here we stu
dy the four-point magnetoresistance of 50 mu m long single quantum wir
es with widths between 250 and 700 nm from 1.3 to 21 K. A distinct wea
k localization peak and universal conductance fluctuations dominate th
e low magnetic field regime and are used to estimate the phase-coheren
ce length of the electrons. Pronounced 1/B periodic quantum oscillatio
ns at magnetic fields above 1 T are consistent with the picture of wir
es with a square-well shaped confining potential.