Nonlinear transport and fluctuations in polar semiconductors

In this work we investigate the transport of noninteracting electrons coupled to polar optical phonons. We obtain the non-Markovian Langevin-like equations describing both the drift motion and fluctuations. We find the dependences of the drift velocity and the fluctuation level on the applied field. The possibility of the suppression of thermal fluctuations by the external field is predicted. Conditions under which the regime of runaway takes place are found.