We have observed a strong reduction of the tunneling time in a ${\mathrm{Al}}_{0.29}$${\mathrm{Ga}}_{0.71}$As(5.8 nm)/GaAs(12 nm) multiple-quantum-well structure caused by resonances of electrons between the first excited state and the ground state (down to 430 ps) and also between the second excited state and the ground state (down to less than 60 ps), which are adjusted by electric fields. In addition, we provide evidence for the quenching of the excitonic luminescence to be also induced by the resonance from a comparison of the tunneling time and the recombination time.

• Received 30 March 1987

DOI:https://doi.org/10.1103/PhysRevB.36.4558