Impurity-related noise in single-barrier GaAs/AlAs/GaAs resonant tunneling devices

The low-frequency fluctuations of tunneling current in GaAs/AlAs/GaAs single-barrier heterostructure devices were measured for three samples with different Si-planar-doping in the center of 10.2 nm-thick barrier. The diameter of the mesas were close to 100 micrometers. Upon changes of the biasing voltage across the barrier the character of noise spectra also changed - depending on various electron transport mechanisms in the barrier. We emphasise that noise measurement is much more sensitive than simple current-voltage characteristics.