The DC, AC, and noise properties of the GaAs/AlGaAs modulation-doped field-effect transistor channel

The channel noise of a normally-on MODFET has been measured at
T = 300
K as a function of bias and frequency. The results are in good agreement with theoretical predictions for velocity fluctuation noise. A new method is introduced to calculate the correct dependence of the two-dimensional carrier concentration on channel voltage. The measurements indicate that real-space-charge transfer in the bias range considered is negligible.