Spin injection studies into GaAs quantum wells in the presence of confined electrons

We compare the electroluminescence spectra (spectral composition and polarization characteristics) of two types of Fe-based AlGaAs/GaAs n-i-p spin light emitting diodes (spin LEDs). In type A spin LEDs the GaAs quantum well (QW) does not contain any confined carriers, while in type B LEDs the GaAs QW is occupied by confined electrons generated by excess n -type doping in the AlGaAs (n) barrier. Type B LEDs show a significantly smaller circular polarization at the e₁ h₁ feature than type A devices. Other differences include the presence of the e₁ l₁ exciton as well as excitonic phonon replicas in type B LEDs. Possible mechanisms for these differences are discussed.