Nonlinear theory of the current instability in a ballistic field-effect transistor

We study the nonlinear evolution of the current instability in a ballistic field-effect transistor. We show that in the case of small increments, instability results in the establishment of stationary nonlinear oscillations. The amplitude of the oscillations is calculated. We predict peculiarities in the current-voltage characteristic of the transistor. In particular, the differential resistance at zero frequency should show a large step at the instability threshold. {} 1996 The American Physical Society.