Coexistence of conducting and nonconducting phases on the metallic side of the mott transition in photoinjected semiconductors

Abstract

The nonequilibrium steady state of a direct gap semiconductor is studied under high levels of photoexcitation by continuous laser light. The stability of the uniform steady state of itinerant carriers is probed resorting to linear normal mode analysis of the nonlinear equations of evolution for the carrier charge density. Such analysis leads to the determination of the wavevector dependent electronic contribution to the dielectric function. Examination of its behavior allows us to show that in the extremely degenerate regime the carrier system becomes nonmetallic, and displays a coexistence of metallic and nonmetallic phases on leaving that regime: itinerant carriers move in the background of an extended state of bounded electron and hole charge densities. This introduces a new view of Mott transition in photoinjected semiconductors. This complex behavior is a result of collective together with dissipative effects in the far from equilibrium carrier system governed by nonlinear dynamic laws.