Abstract
The spin polarization of electrons photoemitted from (110) GaAs by irradiating with circlarly polarized light of energy eV was measured by Mott scattering. The GaAs surface was treated with cesium and oxygen to obtain a negative electron affinity (NEA). The spectrum of spin polarization exhibits a peak () at threshold arising from transitions at and positive () and negative () peaks at 3.0 and 3.2 eV, respectively, arising from transitions at . Anomalous behavior, consisting of a depolarization at threshold and an increase and shift in the peak polarization to 54% at 1.7 eV, is attributed to a small positive electron affinity (PEA) characteristic of some samples. Restriction of the photoelectron emission angle by the PEA leads directly to the anomalously high . Results of calculations show that cannot be increased above 50% for emission arising from transitions at in NEA GaAs. Our detailed interpretation of the spectra indicates how spin-polarized photoemission can be used to study the spin-dependent aspects of electronic structure. The outstanding qualities of NEA GaAs as a source of spin-polarized electrons are discussed and compared with other sources.
- Received 10 February 1976
DOI:https://doi.org/10.1103/PhysRevB.13.5484
©1976 American Physical Society