TIME-RESOLVED SPECTROSCOPY OF ELECTRON DECAY IN COUPLED QUANTUM-WELLS- OBSERVATION OF RELAXATION INDUCED SLOW-DOWN

Electron decay from symmetric coupled quantum wells through a potentia l barrier to a continuum is studied using time resolved optical spectr oscopy. We find that at the limit of a thin barrier the decay rate dec reases with decreasing barrier thickness and the energy splitting betw een the electron levels disappears. We show that this behavior is gene ral for systems where resonant tunneling is coupled to a relaxation ch annel.