Electrical control of optical orientation of neutral and negatively charged excitons in an n-type semiconductor quantum well

-type GaAs/AlGaAs quantum well. Under resonant excitation of free neutral heavy-hole excitons, thepolarization of trions increases dramatically with electrical injection of electrons. The polarization enhance-ment correlates strongly with trion/exciton luminescence intensity ratio. This effect results from a very efficienttrapping of free neutral excitons by the quantum well interfacial fluctuations “natural” quantum dots con-taining resident electrons.DOI: 10.1103/PhysRevB.75.033317 PACS number s : 71.35. y, 73.21. b, 78.67. n, 85.75. d