Removal of hydrocarbon contamination and oxide films from atom probe specimens

Abstract

Many materials science phenomena require joint structural and chemical characterization at the nanometer scale to be understood. This can be achieved by correlating electron microscopy (EM) and atom probe tomography (APT) subsequently on the same specimen. For this approach, specimen yield during APT is of particular importance, as significantly more instrument time per specimen is invested as compared to conventional APT measurements. However, electron microscopy causes hydrocarbon contamination on the surface of atom probe specimens. Also, oxide layers grow during specimen transport between instruments and storage. Both effects lower the chances for long and smooth runs in the ensuing APT experiment. This represents a crucial bottleneck of the method correlative EM/APT. Here, we present a simple and reliable method based on argon ion polishing that is able to remove hydrocarbon contamination and oxide layers, thereby significantly improving APT specimen yield, particularly after EM.