Electrical spin injection across air-exposed epitaxially regrown semiconductor interfaces

We have fabricated spin-polarized light-emitting diode structures via epitaxial regrowth of Zn_l-xMn_xSe on air-exposed surfaces of Al_yGa_l-yAs/GaAs quantum wells. No passivation procedures were used to protect or prepare the III-V surface. The electroluminescence is strongly circularly polarized due to the electrical injection of spin-polarized electrons from the ZnMnSe contact into the GaAs quantum well. An analysis of the optical polarization yields a lower hound of 65% for the spin injection efficiency. These results demonstrate the robustness of the spin injection process in the diffusive transport regime, and attest to the practicality of manufacturing semiconductor-based spin injection devices.