High luminescence polarization of InGaAs-AlGaAs strained layer superlattice fabricated as a photocathode of spin-polarized electron source

High circular luminescence polarization of 65% was observed in the InGaAs-A lGaAs strained layer superlattice which was fabricated as a spin-polarized electron source. The dependence of photoluminescence polarization on the ex citation photon energy was well explained by the calculated band structure of the sample. The spin relaxation time and the lifetime of photo-generated electrons in the conduction band were determined from the experimental res ults of the time-resolved photoluminescence measurement. The spin polarizat ion of conduction band electrons at the instant of excitation was determine d to be 94% from the photoluminescence polarization, the lifetime and the s pin relaxation time.