PRODUCTION OF SPIN-POLARIZED ELECTRONS BY PHOTOEMISSION FROM GAAS(110)

The properties of the spin-polarized electron source based on photoemission from Zn-doped GaAs depend on the degree of surface coverage with cesium and oxygen. In the case of a negative-electron-affinity surface a systematic depolarization of the emitted electrons takes place by exchange scattering in the Cs-O overlayer. It is deduced from the temperature dependence of the spin polarization that electrons which have for h>1.8 eV thermalized into the L valley are less depolarized in the overlayer as well as in the bulk than the electrons which stem from the point. Accordingly we suggest that the L-point electrons be used in a source of polarized electrons, and present our specific and simple design. © 1979 The American Physical Society.