On the temperature dependence of the mass spectra of AuGe and AuGeSi liquid metal alloy ion sources

This reports on an extensive study of the characteristics of AuGe and AuGeSi liquid metal alloy ion sources as a model system for new semiconductor compatible FIB sources. Such characteristics include ion beam mass spectra. A careful investigation has been undertaken where the emitter temperature is the main variable parameter. This work concerns the temperature dependence of the mass spectra of two needle-type liquid metal alloy ion sources (LMAISs), namely Au77Ge14Si9 (Tm=364°C) and Au73Ge27 (Tm=365°C). The sources are importan for producing SiGe layers. The experimental results, in conjunction with existing theories, strongly points towards the co-existance of twomechanisms for the emission of doubly-charged monomer ions: direct field-evaporation and post-ionisation.