Spin injection from (Ga,Mn)As into InAs quantum dots

Using a spin light emitting diode (spin-LED) we study the injection of spin-polarized holes and electrons from a (Ga,Mn)As epitaxial film into self-assembled InAs quantum dots (QDs). The electroluminescence polarization, integrated over the QD ensemble, is {~}1% for both carrier types, consistent with quantum well (QW) spin-LEDs. However, spectrally resolved measurements reveal a monotonic decrease in polarization with increasing energy for hole injection, while no spectral dependence is observed for electron injection. This is in contrast to previous measurements of QW based structures.