Spin-polarized photoemission from AlGaAs/GaAs heterojunction: A convenient highly polarized electron source

Abstract

We analyze the operation of a spin-polarized electron source, consisting of a 100 Å GaAs cap on top of Al0.3Ga0.7As, excited at 300 or 120 K by a He-Ne laser. The cap allows easy activation to negative electron affinity while the alloy permits gap matching to the light source, and thus large electron spin polarization (30% at 300 K, 36% at 120 K). We compare yield curves, energy distribution curves, and polarized energy distribution curves obtained on samples with 100 and 1000 Å caps and on bulk GaAs. The X conduction minimum position in the alloy is also determined.