High-Field Microwave Permittivity of Electrons in Bulk GaAs

Measurements of the permittivity of bulk n-type GaAs have been obtained at a frequency of 35 GHz with microwave heating field strengths up to 16 kV/cm. The measurements are in good agreement with predictions of a simple two-valley model using an energy-independent thermal relaxation time τT=1.5×10−12 sec. The peak value of the large-signal permittivity is found to be considerably smaller than the small-signal high-field values reported in the past. This disparity is substantiated by calculations with the two-valley model. It is felt that the large-signal function measured here is considerably more relevant to LSA-mode circuit design, as well as to calculations of electron parametric operation, than small-signal values.