Dissipative ordered structures of exciton systems in semiconductors
Recently the systems with quantum dots, quantum wires and quantum wells are of great interest because of the application in electronics. Also the research of interaction between electronic excitations under intensive laser irradiation of those systems is popular. At the same time, new phases can be formed, and these phases exist only during the time of the irradiation. At the present contribution, the condensed phases of interacting excitons, which are created by laser irradiation in semiconductor quantum wells, is investigated. A phenomenological theory of phase ordering of excitons under inhomogeneous laser excitation is proposed. It is applied to explain the recent experiments about the appearance of exciton emission ring and the ring structure at macroscopic distances around the laser spot [1, 2]. The exciton density equation, which includes the existence of the gas and condensed phases of excitons in Landau model, is under consideration. Under axially symmetric exciton generation rate, a continuous-ring solution is unstable and obeying certain conditions the continuous ring of excitons breaks up into periodically sited islands of the condensed phase. The transitions between the fragmented and continuous rings depending on the electron-hole recombination rate, the surface energy and temperature are investigated. The fragmentation of the ring is accounted for the processes of self-organization in the system of condensed excitons and
can be regarded as ordered structures formation in a non-equilibrium system.