ELECTRON-SPIN POLARIZATION IN PHOTOEMISSION FROM THIN ALXGA1-XAS

The polarization of photoemitted electrons from thin AlxGa1-xAs layers grown by molecular-beam epitaxy has been studied as a function of Al concentration by varying x in steps of 0.05 from 0.0 to 0.15. As the fraction x is increased, the wavelength dependence of the polarization shifts toward shorter wavelengths, permitting wavelength tuning of the region of maximum polarization. A maximum electron polarization of 42%-43% is obtained for AlxGa1-xAs samples with x greater-than-or-equal-to 0.05 while the maximum polarization of GaAs (x=0) samples reaches 49%. To investigate the lower polarization of AlxGa1-xAs, additional samples have been studied, including a short-period superlattice (GaAs)7 - (AlAs)1.