Field Ion Emission in an Atom Probe Microscope Triggered by Femtosecond-Pulsed Coherent Extreme Ultraviolet Light

Abstract

This paper reports construction of an extreme ultraviolet (EUV) radiation-triggered atom probe tomograph and describes the results from initial experiments on amorphous SiO2. Femtosecond-pulsed coherent EUV radiation of 29.6 nm wavelength (41.85 eV photon energy), obtained through high harmonic generation in an Ar filled hollow waveguide, triggers ion emission from the specimen apex. The composition measured in EUV atom probe tomography (APT) was stoichiometric to within the error of our measurement. EUV radiation offers a new, promising alternative to near-ultraviolet (NUV) laser atom probe tomography. It is especially promising for the analysis of materials that suffer from low absorption in the NUV band and those where the composition is not known a priori. The possible thermal and athermal ion emission mechanisms that may be operating in EUV APT are discussed.