Voltage-controlled hole spin injection in nonmagnetic GaAs/AlAs resonant tunneling structures

We have investigated polarization-resolved photoluminescence under applied voltage in p-i-p GaAs/AlAs double-barrier diodes. We have observed oscillations in the degree of polarization up to 36% at B=15 T with sign reversals occurring near to the hole subband resonances. At high voltages a polarization saturation up to 25% at B=15 T is observed. The data are interpreted by using simulations based on a simple theoretical model that considers spin conservation for tunneling and the relaxation processes for carriers at Zeeman states in the quantum well. Our work offers the prospect for the development of voltage-controlled spin filtering systems using standard nonmagnetic semiconductor heterostructures.731