Carrier dynamics in active-region materials for diode laser applications

摘要

We report on the transient photoluminescence behavior of InAs/GaAs quantum dots. Quasi-instantaneous excitation by femtosecond pulses and luminescence detection by a synchro-scan streak-camera allows for monitoring transients in the range between 7 ps and several ns. For the practical application of novel micro- and nanostructures as active region materials of optoelectronic devices, knowledge about their behavior at high non-equilibrium carrier densities as well as about the carrier dynamics within such complex systems is required. Obtaining insight into these elementary processes allows for the estimation of potential application fields and perspectives of given structures and device concepts. We analyze the carrier transfer between quantum dots. In particular we address the lateral transfer within one dot-plane, the vertical transfer between different dot planes in stacked arrays, as well as the vertical transport between dot planes, where the heights of the potential barriers are externally controlled. For these model systems, we discuss the recombination behavior, aspects such as carrier trapping, and carrier localization as well as the carrier transfer between different parts of the structures.