Quartz-Crystal Microbalance Technique for the Preparation of Alkali-Antimonide Photocathodes

Abstract

A quartz‐crystal microbalance technique has been developed which measures the chemical composition of an alkali‐antimonide film during photocathode formation at the normal photocathode processing temperatures. It is possible to measure continuously and simultaneously the chemical composition, photoelectric emission, resistance, and optical transmission of the alkali‐antimonide during photocathode formation. A thermal ionization source, which acts as a relative partial pressure indicator, yields additional data on the kinetics of the reaction mechanisms. Results are reported for the Cs–Sb and the K–Sb systems. The data indicate the importance of the experimental parameters (antimony film thickness, temperature, and alkali‐metal. vapor pressure) upon the reaction rates. Correlation of electro‐optical properties with composition depends on a knowledge of these parameters.