Surface Ionization Source for Ion Implantation

Abstract

A surface ionization source was designed and developed to produce useful ion beams of elements with ionization potentials up to about 6 eV by using iridium (work function 5.27 eV) as the ionizing surface. Sources were operated successfully producing stable ion beams of aluminum, gallium, indium, and thallium with current densities up to 10 μA/cm2. Neutral atoms are shielded from the beam as it leaves the source by a special design geometry. The construction, developmental details, and operating parameters of the source are described.