J. Appenzeller et al., ELECTRON INTERFERENCE IN A T-SHAPED QUANTUM TRANSISTOR BASED ON SCHOTTKY-GATE TECHNOLOGY, Physical review. B, Condensed matter, 53(15), 1996, pp. 9959-9963
We have observed quantum interference in the electronic transport in a
T-shaped Al0.3Ga0.7As/GaAs heterostructure. The geometry is defined b
y four independent Schottky gates on top of the layer system. By chang
ing the split-gate voltages, the dimensions of the T-shaped two-dimens
ional electron gas could be varied continuously. Especially, the stub
length of the transistor can be controlled in order to switch between
constructive and destructive interference. An additional advantage of
using gates instead of etching methods to define the geometry is the s
mooth form of the boundary potential which implies specular boundary s
cattering. At low temperatures the transport in the high mobility two-
dimensional electron gas (2DEG) is ballistic. Thus weak-localization e
ffects and conductance fluctuations are suppressed, whereas the intend
ed interference pattern is reproducible and nearly identical for diffe
rent samples. We attribute the observed resistance oscillations to the
change in transmissivity in the device when the geometry is altered.
Other explanations are discussed as well but could be excluded by expe
riment.