Dissipative ordered structures of exciton systems in semiconductors
Abstract:
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.