Generation-recombination noise in the saturation regime of MODFET structures

Low-frequency noise measurements were performed on n-GaAs/undoped AlAs superlattice MODFET structures in the temperature and frequency ranges from 50 to 270 K and 1 Hz to 25 kHz, respectively. In both the ohmic and the velocity-saturated regime, generation-recombination (g-r) noise was dominant. Two electron traps were detected. The structure of the noise spectra in the velocity-saturated and ohmic regime were similar, but were smaller by several orders of magnitude in the latter case. For temperatures above 250 K the measurements show an additional 1/f noise at low frequencies in the velocity-saturation regime. A model that explains the g-r noise in the velocity-saturated part of the channel is proposed and applied successfully to the experimental data