Spin-polarized light-emitting diode using metal/insulator/semiconductor structures

We have succeeded in growing ferromagnetic metals (Co, Fe, and NiFe)/Al2O3/AlGaAs heterostructures with homogeneous flat interfaces. The electroluminescence from a light-emitting diode with a metal/insulator/semiconductor (MIS) structure depends on the magnetization direction of the ferromagnetic electrode. This fact shows that a spin injection from the ferromagnetic metal to the semiconductor is achieved. The spin-injection efficiency is estimated to be the order of 1% at room temperature. (C) 2002 American Institute of Physics.