ENERGY-TRANSFER PROCESSES VIA THE INTERFACE OF ZNSE GAAS EPILAYERS/

In the present paper, energy transfer processes via the interface of m olecular beam epitaxy (MBE) grown ZnSe/GaAs epilayers are investigated by means of time-resolved photoluminescence spectroscopy. High excita tion experiments show that an electron-hole plasma exists in free-stan ding ZnSe layers only. By comparing the time-resolved luminescence pro perties of ZnSe/GaAs heterostructures and of free-standing ZnSe layers , we demonstrate which kind of energy transfer mechanism is predominan t in heterostructures: At low excitation densities energy is transfere d by re-absorption of the ZnSe luminescence. At higher excitation dens ities, an ambipolar carrier diffusion via the ZnSe/GaAs interface is t he dominating process.