Growth and characterization of GaAs-based spin-polarized photocathodes

Spin-polarized electron sources find application in both high-energy and nuclear physics experiments. We describe in detail the design and characterization of different photocathodes based on GaAs/GaAsP superlattice structures. These structures are fabricated with a Distributed Bragg Reflector (DBR) aimed at achieving a high quantum efficiency (QE)~ 20% in addition to a high electron spin polarization (ESP) ~85% at the desired wavelength of 780 nm. We present the QE and ESP measurements of photoemitted electrons as a function of wavelength of incident light, along with morphological and photoluminescence measurements.