  Semiconductor structures using ferromagnetic semiconductors as spin injectors
are promising systems for future spintronic devices. Here, we present combined
photoluminescence (PL) and time-resolved magneto-optical experiments of a
nominally nonmagnetic quantum well(QW) separated by a thin barrier from a
ferromagnetic Ga(Mn)As layer. Due to the partial quenching of the PL, we
conclude that there is a significant Mn backdiffusion into the QW. Moreover,
from the time-resolved measurements, we infer that the Mn leads to n-type
doping within the QW, and, in addition, strongly increases the electron spin
dephasing time.
