XPS AND UHV-AFM ANALYSIS OF THE K 2 CsSb-PHOTOCATHODE GROWTH ∗

Alkali-Antimonide growth was examined at the Center of Functional Nanomaterials (CFN) at Brookhaven National Laboratory (BNL). The materials were grown in a UHV chamber and analyzed by means of core-level xray electron spectroscopy (XPS) and UHV-atomic-force microscopy (UHV-AFM). We were able to grow CsK2Sb cathodes with an average quantum efficiency around 12.5 % under good vacuum conditions.The findings will be compared to materials grown under less favorable conditions with water partial pressures of up to 1·10 −7 Torr during evaporation. It appears that cathodes grown within a high water partial pressure environment can show up to 1% quantum efficiency but usually showed none.