UC San Diego

Photocathodes are devices where electrons are emitted upon illumination by a light source. This dissertation investigates how optical resonances can be used to increase the efficiency of both metal and semiconductor cathodes. We theoretically investigate the use of interferences via surface plasmons created on subwavelength gratings of aluminum photocathodes. We predict that plasmonic cathodes could have a ~30x improvement over non-resonant aluminum cathodes and should be substantially more efficient than the currently used Cu cathodes. We also investigate the use of interferences to enhance the efficiency of thin film semiconductor cathodes. Interferences from silver, gold, and aluminum backed photocathodes could increase the efficiency of cathodes by as much as 30% over bulk photocathodes, and even greater enhancement for thinner cathodes, particularly as compared to current commonly used substrates.