MEASUREMENT OF THE QUANTUM EFFICIENCY OF CSI, AMORPHOUS-SILICON AND ORGANOMETALLIC REFLECTIVE PHOTOCATHODES

We performed a systematic investigation of the quantum efficiency of s ome solid reflective photocathodes in the spectral range 140-240 nm. T he measurements were made without gaseous amplification in vacuum and in methane. No significant difference was found among CsI photocathode s prepared by vacuum deposition at different institutes, either from p owders or from crystals of different origins, and measured either in v acuum or in methane. Amorphous silicon photocathodes were prepared by the plasma enhanced chemical vapor deposition technique. We present th e results for several doping conditions of amorphous silicon and for p -n junctions. Some organometallic photocathodes, containing iron or ot her transition metals (cerium), were evaporated and measured. Among th em decamethylferrocene exhibits the highest quantum efficiency in the range 190-240 nm.