Local Electrode Atom Probes

1998 ◽  
Vol 4 (S2) ◽  
pp. 84-85
Author(s):  
Thomas F. Kelly ◽  
Patrick P. Camus
Keyword(s):  
Thin Film ◽  
Data Collection ◽  
Atom Probe ◽  
Atomic Scale ◽  
Specimen Geometry ◽  
Resolving Power ◽  
Charge Ratio ◽  
Atom Probes ◽  
Mass Resolving Power ◽  
Analytical Standards

The Need for Improvements. Though atom probe techniques have impressive atomic-scale analytical capabilities, there are some definite needs for improvement. The needle shape of APFIM specimens is a difficult geometry to make for many types of materials, especially technologically important thin-film materials. Even though 3DAPs collect more data than traditional APs, the analysis volumes are still small by analytical standards: typically there are fewer than 1 million atoms in an image which is about 15nm x 15nm x 50nm. The data collection rate (up to tens of atoms per second) limits the practical size of analyzed volumes to about 1 million atoms. Poor mass resolution makes it difficult to separate ions of similar mass-to-charge ratio in spectra of approximately 20% of samples. Thus, there are three principal areas where improvements are desirable: 1) specimen geometry, 2) data collection rates, and 3) mass resolving power.

Thin film underlayer effects on mass resolving power in laser-assisted atom probe tomography

2014 ◽  
Vol 551 ◽  
pp. 32-36 ◽  
Author(s):  
K. Tippey ◽  
J.G. Brons ◽  
M. Kapoor ◽  
B. Fu ◽  
G.B. Thompson
Keyword(s):  
Thin Film ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

On the Field Evaporation Behavior of a Model Ni-Al-Cr Superalloy Studied by Picosecond Pulsed-Laser Atom-Probe Tomography

2008 ◽  
Vol 14 (6) ◽  
pp. 571-580 ◽  
Author(s):  
Yang Zhou ◽  
Christopher Booth-Morrison ◽  
David N. Seidman
Keyword(s):  
Atom Probe Tomography ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Atom Probe ◽  
Resolving Power ◽  
Noise Levels ◽  
Thermally Activated ◽  
Mass Resolving Power

AbstractThe effects of varying the pulse energy of a picosecond laser used in the pulsed-laser atom-probe (PLAP) tomography of an as-quenched Ni-6.5 Al-9.5 Cr at.% alloy are assessed based on the quality of the mass spectra and the compositional accuracy of the technique. Compared to pulsed-voltage atom-probe tomography, PLAP tomography improves mass resolving power, decreases noise levels, and improves compositional accuracy. Experimental evidence suggests that Ni2+, Al2+, and Cr2+ ions are formed primarily by a thermally activated evaporation process, and not by post-ionization of the ions in the 1+ charge state. An analysis of the detected noise levels reveals that for properly chosen instrument parameters, there is no significant steady-state heating of the Ni-6.5 Al-9.5 Cr at.% tips during PLAP tomography.

Understanding of Capping Effects on the Tip Shape Evolution and on the Atom Probe Data of Bulk LaAlO3 Using Transmission Electron Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Chang-Min Kwak ◽  
Young-Tae Kim ◽  
Chan-Gyung Park ◽  
Jae-Bok Seol
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Resolving Power ◽  
Shape Evolution ◽  
Oxide Materials ◽  
Field Evaporation ◽  
Laser Illumination ◽  
Transmission Electron ◽  
Mass Resolving Power

AbstractTwo challenges exist in laser-assisted atom probe tomography (APT). First, a drastic decline in mass-resolving power is caused, not only by laser-induced thermal effects on the APT tips of bulk oxide materials, but also the associated asymmetric evaporation behavior; second, the field evaporation mechanisms of bulk oxide tips under laser illumination are still unclear due to the complex relations between laser pulse and oxide materials. In this study, both phenomena were investigated by depositing Ni- and Co-capping layers onto the bulk LaAlO3 tips, and using stepwise APT analysis with transmission electron microscopy (TEM) observation of the tip shapes. By employing the metallic capping, the heating at the surface of the oxide tips during APT analysis became more symmetrical, thereby enabling a high mass-resolving power in the mass spectrum. In addition, the stepwise microscopy technique visualized tip shape evolution during APT analysis, thereby accounting for evaporation sequences at the tip surface. The combination of “capping” and “stepwise APT with TEM,” is applicable to any nonconductors; it provides a direct observation of tip shape evolution, allows determination of the field evaporation strength of oxides, and facilitates understanding of the effects of ultrafast laser illumination on an oxide tip.

scholarly journals Improved Mass Resolving Power and Yield in Atom Probe Tomography

2013 ◽  
Vol 19 (S2) ◽  
pp. 994-995 ◽  
Author(s):  
D.J. Larson ◽  
T.J. Prosa ◽  
J.H. Bunton ◽  
D.P. Olson ◽  
D.F. Lawrence ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Single-Ion Deconvolution of Mass Peak Overlaps for Atom Probe Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 300-306 ◽  
Author(s):  
Andrew J. London ◽  
Daniel Haley ◽  
Michael P. Moody
Keyword(s):  
Kinetic Energy ◽  
Point Cloud ◽  
Atom Probe ◽  
Resolving Power ◽  
Isotopic Abundance ◽  
Mass Peak ◽  
Peak Overlap ◽  
Mass Resolving Power ◽  
Charge Spectrum ◽  
Isotopic Abundances

AbstractDue to the intrinsic evaporation properties of the material studied, insufficient mass-resolving power and lack of knowledge of the kinetic energy of incident ions, peaks in the atom probe mass-to-charge spectrum can overlap and result in incorrect composition measurements. Contributions to these peak overlaps can be deconvoluted globally, by simply examining adjacent peaks combined with knowledge of natural isotopic abundances. However, this strategy does not account for the fact that the relative contributions to this convoluted signal can often vary significantly in different regions of the analysis volume; e.g., across interfaces and within clusters. Some progress has been made with spatially localized deconvolution in cases where the discrete microstructural regions can be easily identified within the reconstruction, but this means no further point cloud analyses are possible. Hence, we present an ion-by-ion methodology where the identity of each ion, normally obscured by peak overlap, is resolved by examining the isotopic abundance of their immediate surroundings. The resulting peak-deconvoluted data are a point cloud and can be analyzed with any existing tools. We present two detailed case studies and discussion of the limitations of this new technique.

First Data from a Commercial Local Electrode Atom Probe (LEAP)

2004 ◽  
Vol 10 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Thomas F. Kelly ◽  
Tye T. Gribb ◽  
Jesse D. Olson ◽  
Richard L. Martens ◽  
Jeffrey D. Shepard ◽  
...  
Keyword(s):  
Data Collection ◽  
Three Dimensional ◽  
Atom Probe ◽  
Field Of View ◽  
Performance Parameters ◽  
Scientific Instruments ◽  
Materials Analysis ◽  
Collection Rate ◽  
Atom Probes

The first dedicated local electrode atom probes (LEAP [a trademark of Imago Scientific Instruments Corporation]) have been built and tested as commercial prototypes. Several key performance parameters have been markedly improved relative to conventional three-dimensional atom probe (3DAP) designs. The Imago LEAP can operate at a sustained data collection rate of 1 million atoms/minute. This is some 600 times faster than the next fastest atom probe and large images can be collected in less than 1 h that otherwise would take many days. The field of view of the Imago LEAP is about 40 times larger than conventional 3DAPs. This makes it possible to analyze regions that are about 100 nm diameter by 100 nm deep containing on the order of 50 to 100 million atoms with this instrument. Several example applications that illustrate the advantages of the LEAP for materials analysis are presented.

scholarly journals MeasuringContributions to Mass Resolving Power in Atom Probe Tomography

2011 ◽  
Vol 17 (S2) ◽  
pp. 754-755 ◽  
Author(s):  
E Oltman ◽  
T Kelly ◽  
T Prosa ◽  
D Lawrence ◽  
D Larson
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Resolving Power ◽  
Mass Resolving Power

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

The Influence of Experimental Parameters and Specimen Geometry on the Mass Spectra of Copper During Pulsed-Laser Atom-Probe Tomography

2014 ◽  
Vol 20 (6) ◽  
pp. 1715-1726 ◽  
Author(s):  
R. Prakash Kolli ◽  
Frederick Meisenkothen
Keyword(s):  
Pulse Energy ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Atom Probe ◽  
Pulse Frequency ◽  
Resolving Power ◽  
Base Temperature ◽  
Mass Resolving Power ◽  
Half Angle ◽  
Tip Radius

AbstractWe have studied the influence of experimental factors and specimen geometry on the quality of the mass spectra in copper (Cu) during pulsed-laser atom-probe tomography. We have evaluated the effects of laser pulse energy, laser pulse frequency, specimen base temperature, specimen tip radius, and specimen tip shank half-angle on the effects of mass resolving power, (m/Δm), at full-width at half-maximum and at full-width at tenth-maximum, the tail size after the major mass-to-charge state (m/n) ratio peaks, and the mass spectra. Our results indicate that mass resolving power improves with decreasing pulse energy between 40 and 80 pJ and decreasing base temperature between 20 and 80 K. The mass resolving power also improves with increasing tip radius and shank half-angle. A pulse frequency of 250 kHz slightly improves the mass resolving power relative to 100 or 500 kHz. The tail size decreases with increasing pulse energy. The mass resolving power improves when the cooling time is reduced, which is influenced by the thermal diffusivity of Cu and the specimen base temperature.

Atom probes of the future

1994 ◽  
Vol 52 ◽  
pp. 834-835
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
D. J. Larson ◽  
L. M. Holzman
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
3D Images ◽  
New Era ◽  
Atom Probes ◽  
Position Sensitive ◽  
Third Dimension ◽  
Position Sensitive Detectors ◽  
Very High

Atom probe microscopy, which is based on the first ever atomic-scale imaging technique, field ion microscopy (FIM), has entered a new era in its development. Three-dimensional atom probes (3DAP) are now operating which produce 3D images with atomic scale resolution. It appears that the technology will soon be at hand to make 3DAPs do everything that their predecessor, the conventional atom probe, now does and also reach the third dimension. These microscopes will be simpler, smaller, faster, and much more powerful than the conventional atom probe. Several developments are responsible for this suggestion. 1) Rapid pulsing schemes are being developed which will make it possible to achieve on the order of 106 pulses per second. 2) Highspeed position-sensitive detectors (PSDs) have been designed which can detect several ions in a givenpulse with very high precision. 3) New specimen geometries will soon become possible which will revolutionize the atom probe. Let us consider the ramifications of each of these developments in turn.

Progress in the Atomic-Scale Analysis of Materials with the Three-Dimensional Atom Probe

MRS Bulletin ◽  
2001 ◽  
Vol 26 (2) ◽  
pp. 102-107 ◽  
Author(s):  
A. Cerezo ◽  
D. J. Larson ◽  
G. D. W. Smith
Keyword(s):  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
Single Atoms ◽  
Flight Mass Spectrometry ◽  
Atom Probes ◽  
Distribution Of Elements ◽  
The Subject ◽  
The Individual ◽  
Field Ion Microscope

Exactly 50 years ago, E.W. Müller became the first person to observe single atoms, with the aid of the field-ion microscope (FIM). In 1967, with John Panitz and S. Brooks McLane, Müller's invention of the atom probe meant that, in his words, “We can now really deal much more intimately with the individual atoms which we encounter, since we know their names.” By combining position-sensitive detection with the time-of-flight mass spectrometry of single atoms in the atom probe, Cerezo and co-workers in the late 1980s built an instrument capable of reconstructing the three-dimensional (3D) atomic distribution of elements present in a material. The instruments that are capable of microanalysis at this level, called generically 3D atom probes (3DAPs), were the subject of two articles published in MRS Bulletin in 1994. In this article, we review some of the progress in the field since that time, in particular, the expansion of the range of materials problems that can be addressed by this powerful technique.

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