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Effects of Detector Dead-time on Quantitative Analyses Involving Boron and Multi-Hit Detection Events in Atom Probe Tomography

Published

Author(s)

Frederick Meisenkothen, Eric B. Steel, T. J. Prosa, Karen T. Henry, Ratna P. Kolli

Abstract

In atom probe tomography (APT), some elements tend to field evaporate preferentially in multi-hit detection events. Boron (B) is one such element. It is thought that a large fraction of the B signal may be lost during data acquisition and is not reported in the mass spectrum or in the 3-D APT reconstruction. Understanding the relationship between the field evaporation behavior of B and the limitations for detecting multi-hit events can provide insight into the signal loss mechanism for B and may suggest ways to improve B detection accuracy. The present work reports data for nominally pure B and for B-doped Si (NIST-SRM2137) at dose levels two-orders of magnitude lower than that which was previously studied by Da Costa, et al. in 2012, while exploring a Fourier based signal processing approach to resolve same isotope, same charge-state ion pair (e.g. 11B1+/11B1+) information in multi-hit detection events. B concentration profiles collected from SRM2137 specimens qualitatively confirmed a signal loss mechanism is 2 at work in atom probe measurements of B in Si. Ion correlation analysis was used to graphically demonstrate that the detector dead-time results in few same isotope, same charge-state ion pairs being properly recorded in the multi-hit data, explaining why B is consistently under-represented in quantitative analyses. Given the important role of detector dead-time as a signal loss mechanism, three different methods for estimating the detector dead-time were presented. The findings of this study, as demonstrated through Si, apply to all quantitative analyses, not just those involving elements that are preferentially detected in multi-hit events.
Citation
Applied Surface Science

Keywords

atom probe tomography, dead-time, B, dopant, multi-hit, detector efficiency
Created July 29, 2015, Updated February 19, 2017