Production of spin-polarized electrons by photoemission from GaAs(110)

Abstract

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 $h\nu >1.8\mathrm{}$ 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 $\Gamma$ point. Accordingly we suggest that the $L$-point electrons be used in a source of polarized electrons, and present our specific and simple design.