The effects of source temperature and emission current on the mass spectrum and the angular distribution of the ions emitted by an AuSi field ion source

Abstract

An Au 82Si 18 field ion source has been investigated. The mass spectrum and the angular distribution of the total emission current and of Au +, Si 2+, Au 2+ and Si + ions have been studied at different temperatures, and a strong influence of temperature has been discovered. The angular distributions of Au + and Si 2+ are composed of two peaks while the angular distributions of Au 2+ and Si + have only one peak. When the temperature is increased, the two peaks of the angular distribution curves move closer one to another and the asymmetric outline of the angular distribution curves of the total emission current becomes smoother and acquires an ideally symmetric form. Increasing the emission current causes a broadening of the angular distribution curves.