Improved electron yield and spin-polarization from III-V photocathodes via bias enhanced carrier drift

Gregory A. Mulhollan, John Bierman, Axel Brachmann, James E. Clendenin, Edward Garwin, Robert Kirby, Dah An Luh, Takashi Maruyama, Richard Prepost

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Spin-polarized electrons are commonly used in high energy physics. Future work will benefit from greater polarization. Polarizations approaching 90% have been achieved at the expense of yield. The primary paths to higher polarization are material design and electron transport. Our work addresses the latter. Photoexcited electrons may be preferentially emitted or suppressed by an electric field applied across the active region. We are tuning this forward bias for maximum polarization and yield, together with other parameters, e.g., doping profile. Preliminary measurements have been carried out on bulk and thin film GaAs. As expected, the yield change far from the bandgap is quite large for bulk material. The bias is applied to the bottom (non-activated) side of the cathode so that the accelerating potential as measured with respect to the ground potential chamber walls is unchanged for different frontto-back cathode bias values. The size of the bias to cause an appreciable effect is rather small reflecting the low drift kinetic energy in the zero bias case.

Original languageEnglish
Title of host publicationProceedings of the Particle Accelerator Conference, PAC 2005
Number of pages3
StatePublished - 2005
EventParticle Accelerator Conference, PAC 2005 - Knoxville, TN, United States
Duration: 16 May 200520 May 2005

Publication series

NameProceedings of the IEEE Particle Accelerator Conference


ConferenceParticle Accelerator Conference, PAC 2005
Country/TerritoryUnited States
CityKnoxville, TN


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