Steady-state polarization waves in photoexcited n-doped semiconductors

Abstract

We show that, in n-doped semiconductors under continuous laser illumination the homogeneous steady-state of carriers becomes, in the degenerate regime, unstable against the formation of spatial order at the macroscopic level. Beyond a critical distance from equilibrium this nonequilibrium phase transition occurs, corresponding to the formation of a polarization wave of electrons and holes. It is the result of the interplay of collective and nonlinear dissipative effects in the far-from-equilibrium system.