Power-law photoluminescence decay in indirect gap quantum dots

摘要

In a certain contrast to the standard expectation, according to which the photoluminescence intensity decay in quantum dots could have the mathematical form of exponential function, some experiments indicate a slower type of the intensity decay development, namely in the form of the power-law functional dependence. We are presenting a theoretical interpretation of this phenomenon based on the elec-tron-phonon interaction taken into account in an approximation going beyond the limits of the perturbation theory. We use a simple though quite realistic model of two electronic bound states representing the basic features of the electron in the conduction band states of the InAs small quantum dot. Within this model, the photoluminescence intensity is connected with the electronic level occupation up-conversion process. The electron-phonon coupling is taken into account with the help of the quantum kinetic equations developed with the nonequilibrium Green's functions.