  A fluctuation theory is presented for the nonequilibrium second order phase
transition in a quasi-two-dimensional electron gas. A transverse (with respect
to the current through the sample) spontaneous electric field as an order
parameter and a driving longitudinal field as a control parameter are used. In
addition to the earlier results, the intrawell dynamics is taken into account.
Non-monotonous behavior of the periodic signal gain as a function of the noise
power (stochastic resonance) is predicted.
