Enhancing the Design of Strained Superlattice Gallium Arsenide Based Photocathodes with Distributed Bragg Reflector

Particle accelerators play a crucial role in our understanding of matter and the universe and have numerous practical applications in various fields. These devices enable scientists to examine the smallest components of matter, study the forces that govern their interactions, and probe conditions from the early universe. Moreover, accelerators are valuable in medicine, industry, and research, enhancing imaging methods, cancer therapies, and manufacturing techniques. As the experiments conducted at these facilities evolve and require higher precision, improved particle sources must continue to advance to keep up with their requirements. To do that, we enhanced the design of spin polarized electron sources based on strained GaAs/GaAsP quantum wells to enhance the polarization of the devices and used a distributed Bragg reflector to enhance quantum efficiency. The development of a model that accurately represents the behavior of the key components within these particle sources was crucial in advancing these devices beyond their current capabilities. Studies were then conducted using the modeled behavior of these sources to produce devices capable of meeting the needs of current and future accelerator facilities by notably modifying the number of pairs in the superlattice as well as their compositions, the number of pairs in the distributed Bragg reflector, and several deposition processes to reduce defect formation. We observed spin polarizations as high as 93.65% in our DBR photocathodes with quantum efficiencies reaching up to 2.50%, as well as the ability to extract 11.6 nC of bunch charge, meeting the standard to run the electron-ion collider.