Carrier dynamics in laterally strain-modulated InGaAs quantum wells

摘要

Ute Zeimer; Joerg Fricke; Arne Knauer; Heiko Kissel; Markus Weyers; Georgiy G. Tarasov; J. Grenzer; U. Pietsch We investigate the transient recombination and transfer properties of nonequilibrium carriers in an In_(0.16)Ga_(0.84)As/GaAs quantum well (QW) with an additional lateral confinement implemented by a patterned stressor layer. The structure thus contains QW- and quantum-wire-like areas. At low excitation densities, photoluminescence (PL) transients from both areas are well described by a rate equation model for a three-level system with a saturable interlevel carrier transfer representing the lateral drift of carriers from the QW regions into the wires. Small-signal carrier lifetimes for QW, wires, and transfer time from QW to wire are 180, 190, and 28 ps, respectively. For high excitation densities the time constants of the observed transients increase, in agreement with the model. In addition, QW and wire PL lines merge indicating a smoothening of the potential difference, i.e., the effective carrier confinement caused by the stressor structure becomes weaker with increasing excitation.