Speaker
Description
Researchers at University of California Santa Barbara and Jefferson Lab investigated growth of high polarization heterostructure GaAs photocathodes using either chemical- or molecular-beam epitaxy (CBE or MBE). High polarization photocathodes are required to generate electron beams for particle accelerator physics experiments, and there is an urgent need to to re-establish a source of high polarization photocathode material. Due to the typical challenges for growing "standard" GaAs/GaAsP photocathodes in an MBE or CBE system, the UCSB team began investigating InAlGaAs/AlGaAs, which has been demonstrated as a candidate for high spin polarization and high quantum efficiency (QE). Several variations on InAlGaAs/AlGaAs superlattice photocathodes with varied In and Al content, including those with distributed Bragg reflector (DBR) structures to enhance QE, were grown and tested. Promising results of spin polarization of 80% and QE of 0.3% will be presented.
