Aiming performance of the atom probe

Abstract

We evaluate the aiming performance of our artifact‐free energy focused atom‐probe FIM employing bright contrast rhenium atoms in tungsten alloys as target atoms. The aiming efficiency averaged over the entire surface is 42% with the maximum of 60% on the (011) plane limited by the efficiency of the dual channel plate detector. We conclude that aiming through a 4.7×10⁻⁴ sr angular aperture is nearly perfect, and that aiming errors due to ion trajectory deviation as seen by multilayer field desorption patterns are minimal. Aiming capability is further established by the identification of bright impurity atoms in rhodium specimens as due to 0.1% platinum. Depth profiling of dilute constituents which do not provide visibility contrast is facilitated when the base metals such as V, Fe, Ni, W, or Pt have one or more low‐abundance natural isotopes which may be employed for counting and evaluating the statistical errors. This is demonstrated with the ¹⁹²Pt isotope for the case of Pt–0.1% Mo.