Tunneling through single AlGaAs barriers

Tunneling transfer through Alsub0.35Gasub0.65As barriers is studied in asymmetric double quantum well structures 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 reserve 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 integrated square root of the tunneling barrier height and are an order of magnitude faster than resonant hole tunneling times. The n=2 to n=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

Resonances in tunnelling between quantum wells

Time-resolved photoluminescence measurements in the picosecond regime on GaAs/Al0.35 Ga0.65As asymmetric double quantum well structures with perpendicular electric fields applied in both directions are reported. A large number of electron and hole resonances are detected. A splitting of the ground state resonances reveals the importance of excitonic effects. Longitudinal optical phonon assisted tunnelling plays a minor role for narrow quantum wells in comparison with impurity or interface roughness assisted transfer. Resonant electron tunnelling times depend exponentially on the square root of the effective barrier height and are an order of magnitude shorter than resonant hole tunnelling times

Time-resolved optical investigation of tunneling of carriers through single AlxGa1-xAs barriers

An asymmetric double quantum well structure consisting of a wide and a narrow quantum well separated by AlsubxGasub1minusxAs barriers of various thicknesses is used to investigate resonant and nonresonant tunneling of electrons as well as holes through a single barrier. The carrier transfer times are obtained by tracing the luminescence decay of the two quantum wells with picosecond time resolution as a function of an applied electric field. For the first time, resonant and nonresonant electron and hole tunneling times in one single structure are reported. Our results are compared with those of other groups. Idealized theoretical models cannot explain the experimental values

Time-resolved optical studies of coupling in CdTe/CdMnTe asymmetric double quantum wells

Tunneling in asymmetric double quantum wells (ADQWs) CdTe/CdMnTe where one of the QWs contains Mn is studied for different tunneling barrier thickness. From time-resolved photoluminescence (TRPL) experiments at various temperature up to 80K, tunneling times and radiative lifetimes are extracted