Nanoscale focused ion beam from laser-cooled lithium atoms

Abstract

We demonstrate a new type of nanoscale focused ion beam (FIB) based on photoionizing laser-cooled atoms held at millikelvin temperatures in a magneto-optical trap (MOT). This new source expands the range of available ionic species and accessible ion beam energies for FIBs, enhancing their role as one of the most important tools for nanoscale characterization and fabrication. We show examples of microscopy with lithium ions obtained by scanning the FIB and collecting the resulting secondary electrons, and characterize the beam focus by a 25–75% rise distance measurement of (26.7 ± 1.0) nm at a beam energy of 2 keV. We also examine the dependence of the focal size on MOT temperature and beam energy.