Spin-polarized injection into p-type GaAs layer from a Co₂MnAl injector

Electric luminescence and its circular polarization in a Co₂MnAl injector-based light emitting diode (LED) has been detected at the transition of e-A_C⁰, where injected spin-polarized electrons recombine with bound holes at carbon acceptors. A spin polarization degree of 24.6% is obtained at 77 K after spin-polarized electrons traverse a distance of 300 nm before they recombine with holes bound at neutral carbon acceptors in a p⁺-GaAs layer. The large volume of the p⁺-GaAs layer can facilitate the detection of weak electric luminescence (EL) from e-A_C⁰ emission without being quenched at higher bias as in quantum wells. Moreover, unlike the interband electric luminescence in the p⁺-GaAs layer, where the spin polarization of injected electrons is destroyed by very effective electron-hole exchange scattering (BAP mechanism), the spin polarization of injected electrons seems to survive during their recombination with holes bound at carbon acceptors.