Observation of extremely long electron-spin-relaxation times in p-type delta-doped GaAs/Al(x)Ga(1-x)As double heterostructures

Spin-relaxation dynamics of electrons have been studied in p-type Delta-doped GaAs:Be/AlsubxGasub1minusxAs double heterostructures by time-resolved photoluminescence polarization measurements. A relaxation time of approximately equal to 20 ns has been observed which is two orders of magnitude longer than that reported for corresponding acceptor concentrations in homogeneously doped GaAs. This enhancement, which arises from a drastic reduction of the electron-hole wave-function overlap, demonstrates that electron- hole scattering with a simultaneous exchange interaction dominates spin relaxation at low temperatures.