Linear, or "Small-signal," theory for the Gunn effect

A model wherein the density of free carriers in the conduction band of a semiconductor is dependent on the electric field and decreases at high fields is considered. The growth and phase velocity of an RF wave of small amplitude which propagates through the medium are evaluated. From these properties the threshold electric field and the frequency tuning characteristics vs. electric field for an oscillating sample are calculated. In high-resistivity samples are predicted 1) the threshold field to increase with increasing resistivity, and 2) the oscillating frequency to decrease when the field is increased above threshold. Experimental data which are consistent with both of these predictions are presented.