Abstract
Time-dependent photoluminescence spectra of ZnO have been measured from 17 K to 295 K. Thermal de-trapping of bound excitons to free excitons is observed. Competition between rates of phonon-assisted broadening and of exciton-exciton inelastic collisions can be discerned as a function of temperature. The velocity of excitation transport across a crystal in resonance with shallow bound excitons 20 meV below the A exciton was measured to be 3.3 10 8 cm/s at 17 K. The phenomenon of oscillator strength enhancement of bound or confined excitons is significant in several of the observations.