Electrical Spin Injection into InGaAs Quantum Dot Ensembles and Single Quantum Dots. - Hetterich, M.; Löffler, W.; Fallert, J.; Passow, T.; Daniel, B.; Lupaca-Schomber, J.; Hetterich, J.; Li, S.; Klingshirn, C.; Kalt, H. (AIP Conference Proceedings, 2007)