Influence of interface roughness on excitonic diffusion in semiconductor quantum well

We report a Monte Carlo investigation on the excitonic diffusion process in semiconductor quantum wells (QW). The rates of interface-roughness scattering and phonon scattering are calculated. By comparing the scattering rates, we find that, in a realistic QW sample with typical well-width and interface quality, the interface-roughness scattering is the dominant mechanism in limiting the diffusivity. Spatiotemporal dynamics of the exciton distribution function are obtained by the simulations and the excitonic diffusivity under different conditions is deduced. We find that the diffusivity increases rapidly with increasing the correlation length of the interface fluctuation and with decreasing the amplitude of the fluctuation. In a typical QW sample, the diffusivity increases exponentially with increasing the width of the well.