NOISE AND REPRODUCIBLE STRUCTURE IN A GAAS/ALXGA1-XAS ONE-DIMENSIONAL CHANNEL

We have analyzed the resistance noise, in the time domain, in a GaAs/Al(x)Ga(1-x)As split-gate device showing quantized resistance plateaus. The noise consists mainly of random telegraph signals which can be related to individual slow-electron-trapping defects within the nonconducting regions of the device. These defects are found to influence the conductance mainly by shifting the average electrical potential of the ballistic constriction (channel) relative to the Fermi level. As the gate voltage is varied the defects change their mean occupancy, and this is shown to give rise to some of the reproducible nonquantized structure in the static characteristics of a device. There is clear evidence for interaction between defects.