MOTIONAL NARROWING IN SEMICONDUCTOR MICROCAVITIES

The linewidths of exciton features in spectra from semiconductor quant um wells normally correspond directly to the width of the probability distribution of the disorder potential causing the broadening. This is because the mass of the exciton is large, so its motion in the potent ial is essentially classical. We show that in a microcavity, where pol ariton mixing leads to much smaller masses, quantum mechanical effects are expected to cause significant spatial averaging over the disorder potential and hence motional narrowing of the spectral Lines. Our pre diction is verified by experimental measurements of linewidths near re sonance in a high quality microcavity structure.