Spin-Polarized Electron Sources Based on Group II-VI Compounds Grown by Atomic Layer Deposition

Harish Bhandari, Radiation Monitoring Devices Inc. (Principal Investigator)

Luca Cultrera, Brookhaven National Laboratory (Co-Investigator)

Photoinjectors producing high spin-polarized electron beams are essential for many accelerator facilities globally, including large-scale projects like Continuous Electron Beam Accelerator Facility (CEBAF) and Electron-Ion Collider (EIC) in the United States, the electron-positron Future Circular Collider (FCC-ee) and International Linear Collider (ILC) off-shore, and for small-scale applications such as Spin-Polarized Low Energy Electron Microscopes (SPLEEM). Current technology relies on Gallium Arsenide (GaAs)-based photocathodes grown through complex and expensive methods like Molecular Beam Epitaxy (MBE) or Metal-Organic Chemical Vapor Deposition (MOCVD). However, challenges with GaAs growth and rising costs necessitate alternative materials.

RMD Inc. proposes using Group II-VI compounds for spin-polarized photocathodes, developed via Atomic Layer Deposition (ALD). This approach aims to bypass the limitations of GaAs and address supply chain risks. Funding for this project will enable collaboration with Brookhaven National Laboratory (BNL) to test and optimize group II-VI photocathodes. This partnership will provide critical feedback, allowing for refinement and validation of the new photocathodes with better performance than the incumbent.

The project will aim to measure quantum efficiency (QE) and spin polarization of Group II-VI photocathodes using BNL’s Mott polarimeter and explore alternative NEA activation methods. RMD will pioneer ALD-grown II-VI cathodes, advancing photocathode technology and enhancing spin-polarized electron beam production for various applications.