Electron spin polarization in the photoemission of NEA GaAs1−x P x

Negative electron affinity GaAs_1–x P _x -photocathodes emit spin-polarized electrons if irradiated with circularly polarized light. The spectra of spin polarization of photoelectrons emitted from crystals with different phosphorus contentx resemble each other in shape but shift to shorter wavelengths with increasingx. Polarization values up to 40% are observed for electrons from crystals withx=0 andx=0.38. Cathodes with higher phosphorus contents increasing fromx=0.65 tox=0.87 and tox = 1.0 deliver photoelectrons with decreasing degrees of spin polarization of 17%, 15%, and 9%, respectively, at maximum.