EXCITON TRANSPORT AND NONRADIATIVE DECAY IN SEMICONDUCTOR NANOSTRUCTURES

A phenomenological theory describing the exciton photoluminescence (PL ) kinetics in type-II superlattices is proposed herein, which takes in to account both the intrinsic exciton radiative decay and nonradiative decay due to exciton trapping by interfacial defects surrounding a '' disordered'' interface, We have thus investigated the effect of system dimensionality on details of these nonradiative-decay kinetics. For e ffectively three-dimensional and two-dimensional structures, the theor y predicts a transition from strongly nonexponential to nearly exponen tial decay kinetics as the temperature is increased. Contrastingly, fo r one-dimensional structures the decay kinetics is predicted to be non exponential at all temperatures. Using these predictions, we have appl ied this model to explain our observed time-resolved PL on specific sh ort-period type-II GaAs/AlAs superlattices. These PL decays are thus e xplained both over a wide range of temperatures (2-30 K) and over an o bserved crossover from nonexponential to exponential behavior. The mod el allows us to extract a nonradiative-defect density and an average r adiative-decay rate from the experimental data. [S0163-1829(98)03940-X ].