Materials Chemistry and Physics, Vol.111, No.2-3, 249-253, 2008
Electric field control photo-induced Hall currents in semiconductors
We generate spin-polarized carrier populations in GaAs and low temperature-grown GaAs (LT-GaAs) by circularly polarized optical beams and pull them by external electric fields to create spin-polarized currents. In the presence of the optically generated spin currents, anomalous Hall currents with an enhancement with increasing doping are observed and found to be almost steady in moderate electric fields up to similar to 120 mV mu m(-1), indicating that photo-induced spin orientation of electrons is preserved in these systems. However, a field similar to 300 mV mu m(-1) completely destroys the electron spin polarization due to an increase of the D'yakonov-Perel' spin precession frequency of the hot electrons. This suggests that high field carrier transport conditions might not be suitable for spin-based technology with GaAs and LT-GaAs. It is also demonstrated that the presence of the excess arsenic sites in LT-GaAs might not affect the spin relaxation by Bir-Aronov-Pikus mechanism owing to a large number of electrons in n-doped materials. (C) 2008 Elsevier B.V. All rights reserved.