Investigations on liquid alloy ion sources for rare-earth elements

Abstract

We have developed liquid alloy ion sources for the rare-earth elements Er and Pr. They can be used in focused ion beam systems for ion implantation into optical materials and superconductors. The rare-earth elements are incorporated into ternary alloys to achieve lower melting points and lower vapor pressures as well as better wetting properties and easier handling of the sources at atmosphere. The melting properties of the alloys were determined by differential thermal analysis. The emission current stability and the mass distribution using a magnetic mass spectrometer and a time-of-flight mass analyzer have been measured. The mass spectra show a high intensity of double charged and a considerable intensity of triple charged Er and Pr ions. The ion sources exhibit a good performance even after storage for several weeks in air.

Investigations on a Co–Dy liquid alloy ion source

“…The high percentage of doubly charged and the presence of triply charged dysprosium ions is typical for LAIS utilizing alloys with rare earth elements. This behaviour was already found for Co-Nd (Hesse et al 1994), Au-Si-Pr (Machalett et al 1996), Au-Er-Si (Machalett et al 1998), Er-Ni (Chao and Steckl (1999), Co-Y (Mühle et al 1998), Au-Dy-Ge and Au-Dy-Si (Mühle et al 2002) and Dy-Ni (Melnikov et al 2002). Brown and Godechot (1991) also found three charge states 1 + , 2 + and 3 + for dysprosium ions in the plasma formed during the arc discharge in a metal vapour vacuum arc (MEVVA) ion source with corresponding particle flux fractions of 2%, 66% and 32%, respectively.…”

A time-of-flight spectrometer for investigations on liquid metal ion sources

“…The obtained results show that the developed spectrometer is a powerful instrument for investigations on liquid metal ion sources, to determine mass spectra and mass resolved energy distributions. A first comparison of our results of ion fraction measurements on an AuErSi LAIS with those of a magnetic spectrometer (Machalett et al 1998) has shown good agreement.…”

Liquid metal ion source working with an Er70Fe22Cr5Ni3alloy

“…Within the last two decades the spectrum of elements available in focused ion beam systems has been enlarged to more than thirty ion species. In the case of an Er LMIS a certain alloy has to be chosen due to the high melting point of Er of 1529 • C. Machalett et al [6] presented alloy LMIS based on the well investigated AuSi compound additionally containing Er or Pr. But these source materials have a low content of the rare earth elements.…”