LARGE ENHANCEMENT OF SPIN POLARIZATION OBSERVED BY PHOTOELECTRONS FROM A STRAINED GAAS LAYER

We have observed a large enhancement of the spin polarization of photoelectrons emmitted from a 0.08-mu-m thick strained GaAs(001) layer grown on a GaPxAs1-x substrate by the MOCVD method with x = 0.17. For this fraction of phosphorus, the lattice-mismatch was estimated to be approximately 0.6% and the energy splitting between heavy-hole and light-hole bands at the valence band maximum to be approximately 40 meV. The maximum polarization of approximately 86% was observed with a quantum efficiency of approximately 2 x 10(-4), under the conditions that the cathode was at room temperature and the excitation photon wavelength was lambda almost-equal-to 860 nm.