Efficient electron spin injection in MnAs-based spin-light-emitting-diodes up to room temperature

Studies of ferromagnetic MnAs in recent years have revealed a wide range of properties desirable for spintronic applications. Previously studied MnAs spin-light-emitting-diodes exhibited a low value of spin injection into the device active region. In this work, we have investigated injection of spin polarized electrons from MnAs into AlGaAs(n)/GaAs(i)/AlGaAs(p) n-i-p structures. The band-edge electroluminescence emitted from these devices has a saturation circular polarization of 26% at 7 K and B=2 T. Using optical pumping measurements the corresponding electron spin polarization was determined to be 52%. Emission persists up to room temperature, with a saturation circular polarization of 6% at B=2 T.