INVESTIGATIONS ON LIQUID ALLOY ION SOURCES FOR RARE-EARTH ELEMENTS

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 impla ntation into optical materials and superconductors. The rare-earth ele ments are incorporated into ternary alloys to achieve lower melting po ints and lower vapor pressures as well as better wetting properties an d easier handling of the sources at atmosphere. The melting properties of the alloys were determined by differential thermal analysis, Tile emission current stability and the mass distribution using a magnetic mass spectrometer and a time-of-flight mass analyzer have been measure d. The mass spectra show a high Intensity of double charged and a cons iderable intensity of triple charged Er and Pr ions, The ion sources e xhibit a good performance even after storage for several weeks in air. (C) 1998 American Institute of Physics. [S0034-6748(98)56802-5].