Ion microscopy based on laser-cooled cesium atoms

TL;DR

This paper presents a prototype laser-cooled cesium ion beam system for high-resolution surface imaging and modification, achieving higher ion yields and promising applications in lithography and surface analysis.

Contribution

It introduces a novel laser-cooled cesium ion source with enhanced ionization efficiency and resolution for focused ion beam applications.

Findings

Ion currents up to 130 pA achieved

Ion yield 40 times larger than standard photo-ionization

Resolution around 40 nm at 1-5 keV ion energy

Abstract

We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130 pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5 keV range are obtained with a resolution around 40 nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of 1 eV, offering great prospects for lithography, imaging and surface analysis.