Electrical spin injection into p-doped quantum dots through a tunnel barrier

The authors have demonstrated by electroluminescence the injection of spin polarized electrons through Co∕Al2O3∕GaAs tunnel barrier into p-doped InAs∕GaAs quantum dots embedded in a p-i-n GaAs light emitting diode. The spin relaxation processes in the p-doped quantum dots are characterized independently by optical measurements (time and polarization-resolved photoluminescence). The measured electroluminescence circular polarization is about 15% at low temperature in a 2T magnetic field, proving an efficient electrical spin injection yield in the quantum dots. Moreover, this electroluminescence circular polarization is stable up to 70K.