Exciton luminescence polarization decay in type II semiconductor heterostructures

In type II semiconductor heterostructures, one can reduce the electron-hole overlap, without changing much the oscillator strength, so that the space indirect exciton luminescence polarization will decay according to the exciton-bound single-particle spin flip. The exciton spin relaxation rate is then limited by the slower single-particle spin-flip rate which is typically the electron one. We discuss the microscopic theory of the exciton-bound electron spin relaxation driven by the spin-orbit k(e)(3) splitting in the conduction band. The exciton-bound electron spin relaxation rate (Wk) is obtained as a function of the material and structure parameters. The exciton luminescence polarization decay rate in AlSb/GaSb/AlSb/InAs/AlSb heterostructures, where space indirect excitons can be created and controled, is estimated. The InAs electron well width L-c dependence is also discussed. (C) 1998 Elsevier Science B.V. All rights reserved.