Tunneling between quantum wells.

Tunneling transfer in various GaAs/Alsub0.35Gasub0.65As asymmetric double quantum well structures is studied by time-resolved photoluminescence measurements in the pico- and femtosecond regime. A large variety of electron and hole resonances is detected when electric fields of both signs are externally applied. The ground state resonance shifts, when the electrons tunnel in the reverse direction, revealing the importance of excitonic effects. Longitudinal optical phonon assisted tunneling plays a minor role for narrow quantum wells in comparison to impurity or interface roughness assisted transfer. Resonant electron tunneling times depend exponentially on the square root of integrated tunneling barrier height and are an order of magnitude faster than resonant hole tunneling times. The n is equal to 2 to n is equal to 1 electronic intersubband scattering time in a 10 nm quantum well is determined to be 550 fs measuring the transfer time through a thin barrier.