Time-resolved photoluminescence is used to study low-temperature-grown (LTG) GaAs with Be doping. It is observed that the carrier trapping time in the as-grown LTG GaAs increases with Be doping. Similar effect is observed also in the annealed samples doped with less than 3×1019 cm−3 of Be. At higher doping levels, the trapping time in these samples is abruptly reduced to below 100 fs. This behavior is attributed to changes in As antisite density and the compensation effect of Be.

Time-resolved photoluminescence transients of low-temperature molecular beam epitaxially grown GaAs layers have been measured with femtosecond temporal resolution and compared with numerical Monte Carlo calculations. It has been shown that the shape of these transients measured at different emission energies is determined not only by the carrier lifetime but also by the electron redistribution in the conduction band. Analysis of the experimental results yields the carrier lifetime in the investigated samples of 400 fs.

We present experimental evidence of inverted photoluminescence spectra in GaAs. The spectra are measured for As-rich GaAs layers with ultrashort (of the order of 30-60 fs) carrier lifetimes. Ensemble Monte Carlo simulations performed using the molecular dynamics approach confirm that the observed PL spectra are generated by non-thermalized carriers several tens of femtoseconds after their excitation.

Observation of excitonic polariton and broadening of roomtemperature exciton in strained InGaAs/GaAs quantum wells

We present direct measurements of interwell carrier transport in InGaAsP quantum well (QW) laser structures performed by time-resolved photoluminescence. Conditions of originally empty and filled wells are explored. In both cases, the time for the hole transport across the structure is found to be of the order of tens of picoseconds. Comparison of experimental results and simulations allowed us to develop an adequate interwell carrier transport model that includes thermionic capture/emission over the QW interfaces and drift/diffusion in the barrier regions. We show that dynamic consideration of carrier densities and band bending for each QW are essential.