FORMATION OF THE Cs2Te PHOTOCATHODE: AUGER AND PHOTOEMISSION SPECTROSCOPY STUDY

The formation of the Cs2Te photocathode on a molybdenum substrate passes through different phases, each of them has been characterised by X-ray photoemission spectroscopy and Auger spectroscopy as well. During the fabrication process different cesium tellurides have been identified in the photoemissive material. The ruggedness to pollution with molecular oxygen at different fabrication stages has been tested. Approximately 5·10-5 sec·torr of exposition reduces the quantum efficiency to one tenth of its original value. The oxidation damage can be partially recovered by simultaneously heating the substrate to ? 230 °C and illuminating it with the 4.9 eV ultraviolet radiation. No recovering has been observed under the effect of the temperature or the radiation alone.