The Use of Surfaces of Rare-Earth Elements to Achieve Durable Negative Electron Affinity Cold Cathodes, Photocathodes, and Polarized Electron Sources

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9906053CahayIn this proposal, we will study both theoretically and experimentally several cathodes and photocathodes fabricated using GaAs and JnP-based materials activated to NEA with NdS and LaS surfaces, respectively. Our ultimate goal is to build prototypes of (1) InP/LaS and GaAs/NdS Schottky barrier transferred electron photoemitters, (2) cold cathodes based on pn GaAs and ImP diodes, (3) JnP/InAlAs and AlGaAs/GaAs cold cathode and photocathode heterojunctions, and (4) GaAsP/GaAs and InP/InAlAs polarized electron sources.Our research effort will consist of a three-year project between the University of Cincinnati (LaS and NdS growth and characterization and device fabrication), Uppsala University (Electronic Structure Calculations), Ovation Semiconductor in Rochester (MN) (MBE growth of III-V heterostructures), Sarnoff Corporation (NJ) (electrical testing of the cathodes), and the Stanford Linear Accelerator Center (SLAC) (test of devices as efficient polarized electron sources).The cold cathodes and photocathodes to be developed in this program could lead to a billion dollar industry due to their wide range of applications including fiat panel displays, photomultipliers, pressure sensors, high-temperature or radiation tolerant sensors, vacuum transistors, and high power microwave tubes. Simultaneously, polarized electron sources find applications in fundamental research in solid state, atomic and high energy physics.***