Effects of intervalley scattering on noise in GaAs and InP field-effect transistors

The results of a dynamic analysis of electron transport in GaAs and InP have been used to determine the effects of device cooling, channel length, and frequency of operation on the noise performance of FET's made of these materials. Noise temperature of the material as a function of electric field is first obtained by an analysis that models intervalley scattering using a Monte Carlo calculation method. Noise figure of the intrinsic device is then obtained using a gradual-channel analysis. The validity of such an analysis is discussed. Both GaAs and InP FET's should exhibit very good low-noise performance, with the intrinsic InP device somewhat noisier than the GaAs device at equivalent values of f/f
T
. For GaAs the intrinsic noise figure can be considerably reduced as the device is cooled, but for InP, cooling from 300 to 77 K should leave intrinsic noise figure almost unchanged.