Nonlocal theory of the size and temperature dependence of the radiative decay rate of excitons in semiconductor quantum dots

A nonlocal theory of the radiative decay rate of excitons in semiconductor quantum dots is developed and the observed size and temperature dependence for CuCl microcrystallites is explained successfully. The retardation effect due to the finite ratio of the quantum dot radius to the wavelength of light is found to be irrelevant for explaining the experiments. Instead, the homogeneous broadening effect is shown to be essential in saturating the mesoscopic enhancement of the excitonic radiative decay rate or, in other words, in determining the effective exciton coherence length.