Time-resolved studies of pulsed electrical spin injection into single InGaAs quantum dots

This study investigates on the circular polarization degree (CPD) anomaly emitted by InGaAs quantum dots within a spin-light emitting diode (spin-LED) with a ZnMnSe spin aligner, when the spin-LED device is excited with nanosecond width pulses. Results show that the change of CPD must be related to spin scattering events. One factor that is responsible to these scattering events is a potential barrier that forms within the spin-LED, which the spin-polarized carriers have to pass by a tunneling process. Hence, tunnelling will only be possible if an empty target state becomes available, such as, after injecting a hole into an occupied dot and subsequent optical recombination.