Electrical manipulation of spin injection into a single InAs quantum dots

We demonstrate spin injection from a n-Zn0.96Mn0.04Se layer into individual InAs quantum dots (SQDs) in a p-i-n diode structure using cw polarization resolved magneto-micro photoluminescence spectroscopy. Interestingly, we find that the spin injection efficiency strongly varies from dot to dot. We obtain a single quantum dot circular polarization degree ranging from 2% to almost 50% (at B=4 T) at zero biasing and within the spectral range studied here, we found 2 maxima of the degree of the circular polarization at SQD energies separated by similar to 33 meV. Importantly, we demonstrate that the spin injection efficiency can be manipulated by external forward biasing (U-ext).