LOW-TEMPERATURE PHOTOLUMINESCENCE OF DISORDERED THIN-LAYER GAAS ALAS SUPERLATTICES - KINETIC-MODEL/

A kinetic model is developed to explain the experimental photoluminesc ence spectra of disordered thin-layer GaAs/AlAs superlattices. It is a ssumed that there exists an exciton level as well as a set of localize d energy levels in the band gap due to disorder. Several kinetic proce sses are included in this model: thermal relaxation from the conductio n band to both the exciton level and the localized states; thermal exc itations from the exciton level and the localized states to the conduc tion band; radiative recombination of the exciton states and localized states; and transitions from localized states to nonradiative centers . The kinetics are investigated both analytically and numerically, and the results obtained are in good agreement with the experimental phot oluminescence behavior.