InP Transferred Electron Cathodes: Basic to Manufacturing Methods.

摘要

InP has gained an emerging importance as a negative electron affinity (NEA) transferred electron photocathode (TEP) material in imaging technologies. InP provides itself as a substrate to grow these small band gap materials, and also serves as an efficient electron emitter with a low work function at the surface. The high quantum efficiency (QE) of these TEP is realized by depositing Cs and O2 on the surface of heavily doped p-type semiconductors, where they form the thin activation layer. The atomic structure of this Cs/O activation layer is, however, not well-known, and the properties of photoelectrons from InP-based cathodes also require careful study. In this study, InP photocathodes were studied in three parts: (1) the atomic arrangement of Cs oxides in the activation layer, (2) the decay mechanism of InP photocathodes in an open UHV system and the simulation of commercial sealed photocathode tubes for the elongation of lifetime, and (3) the energy and angular distribution of photoelectrons from InP photocathodes.