Competition effects in the carrier capture into InxGa1-xAs/GaAs double-quantum-well structures

We report on an experimental study, using continuous-wave and time-resolved photoluminescence spectroscopy, of the carrier capture into InxGa1-xAs/GaAs double-quantum-well structures. We observe oscillations in the carrier collection efficiency as a function of the excitation energy; the counter-phased modulations of the photoluminescence excitation spectra of the two wells clearly demonstrate a competition in the carrier capture into the wells. The time-resolved measurements provide a direct insight on the dynamics of the capture process.