Search query: field ion microscopy

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abstract: Abstract This article reviews recent advances utilizing field ion microscopy (FIM) to extract atomic scale three dimensional images of materials. This capability is not new, as the first atomic scale reconstructions of features utilizing FIM were demonstrated decades ago. The rise of atom probe tomography, and the application of this latter technique in place of FIM has unfortunately severely limited further FIM development. Currently, the ubiquitous availability of extensive computing power makes it possible to treat and reconstruct FIM data digitally and this development allows the image sequences obtained utilizing FIM to be extremely valuable for many material science and engineering applications. This article demonstrates different applications of these capabilities, focusing on its use in physical metallurgy and semiconductor science and technology.
author_names: Francois Vurpillot

Frederic Danoix

Matthieu Gilbert

Sebastian Koelling

Michal Dagan

David N Seidman
title: True Atomic Scale Imaging in Three Dimensions: A Review of the Rebirth of Field Ion Microscopy
venue: Microscopy and Microanalysis
year: 2017

abstract: Abstract An automated procedure has been developed for the reconstruction of field ion microscopy (FIM) data that maintains its atomistic nature. FIM characterizes individual atoms on the specimen's surface, evolving subject to field evaporation, in a series of two dimensional (2D) images. Its unique spatial resolution enables direct imaging of crystal defects as small as single vacancies. To fully exploit FIM's potential, automated analysis tools are required. The reconstruction algorithm developed here relies on minimal assumptions and is sensitive to atomic coordinates of all imaged atoms. It tracks the atoms across a sequence of images, allocating each to its respective crystallographic plane. The result is a highly accurate 3D lattice resolved reconstruction. The procedure is applied to over 2000 tungsten atoms, including ion implanted planes. The approach is further adapted to analyze carbides in a steel matrix, demonstrating its applicability to a range of materials. A vast amount of information is collected during the experiment that can underpin advanced analyses such as automated detection of "out of sequence" events, subangstrom surface displacements and defects effects on neighboring atoms. These analyses have the potential to reveal new insights into the field evaporation process and contribute to improving accuracy and scope of 3D FIM and atom probe characterization.
author_names: Michal Dagan

Baptiste Gault

George D W Smith

Paul A J Bagot

Michael P Moody
title: Automated Atom By Atom Three Dimensional (3D) Reconstruction of Field Ion Microscopy Data
venue: Microscopy and Microanalysis
year: 2017

abstract: Radiation damage in tungsten and a tungsten tantalum alloy, both of relevance to nuclear fusion research, has been characterized using a combination of field ion microscopy (FIM) imaging and atom probe tomography (APT) While APT provides 3D analytical imaging with sub nanometer resolution, FIM is capable of imaging the arrangements of single atoms on a crystal lattice and has the potential to provide insights into radiation induced crystal damage, all the way down to its smallest manifestation a single vacancy. This paper demonstrates the strength of combining these characterization techniques. In ion implanted tungsten, it was found that atomic scale lattice damage is best imaged using FIM. In certain cases, APT reveals an identifiable imprint in the data via the segregation of solute and impurities and trajectory aberrations. In a W 5at%Ta alloy, a combined APT FIM study was able to determine the atomic distribution of tantalum inside the tungsten matrix. An indirect method was implemented to identify tantalum atoms inside the tungsten matrix in FIM images. By tracing irregularities in the evaporation sequence of atoms imaged with FIM, this method enables the benefit of FIM's atomic resolution in chemical distinction between the two species.
author_names: Michal Dagan

Luke R Hanna

Alan Xu

Stephen Roberts

George D W Smith

Baptiste Gault

Philip D Edmondson

Paul A J Bagot

Michael P Moody
title: Imaging of radiation damage using complementary field ion microscopy and atom probe tomography.
venue: Ultramicroscopy
year: 2015

abstract: Alan Cottrell was among the first to recognize the potential of field ion microscopy for the atomic scale study of crystal defects. The study of atomic configurations at the core of dislocations by this method proved to be unexpectedly difficult, because of the mechanical stresses imposed on the specimen by the high electric field. The development of atom probe tomography revitalized such studies. In particular, the atom probe technique permitted the first direct observations of solute atom distributions in the region of dislocations and confirmed the existence of so called 'Cottrell Atmospheres' which are of great importance in the understanding of phenomena such as strain ageing. Atom probe studies of dislocation solute interactions in a diverse range of alloy systems are outlined.
author_names: G D W Smith

D Hudson

P D Styman

Catherine Williams
title: Studies of dislocations by field ion microscopy and atom probe tomography
year: 2013

abstract: The field ion microscope (FIM) can be used to characterize the atomic configuration of the apices of sharp tips. These tips are well suited for scanning probe microscope (SPM) use since they predetermine the SPM resolution and the electronic structure for spectroscopy. A protocol is proposed for preserving the atomic structure of the tip apex from etching due to gas impurities during the period of transfer from the FIM to the SPM, and estimations are made regarding the time limitations of such an experiment due to contamination with ultra high vacuum rest gases. While avoiding any current setpoint overshoot to preserve the tip integrity, we present results from approaches of atomically defined tungsten tips to the tunneling regime with Au(111) HOPG (highly oriented pyrolytic graphite) and Si(111) surfaces at room temperature. We conclude from these experiments that adatom mobility and physisorbed gas on the sample surface limit the choice of surfaces for which the tip integrity is preserved in tunneling experiments at room temperature. The atomic structure of FIM tip apices is unchanged only after tunneling to the highly reactive Si(111) surface.
author_names: W Palmberg Paul

Yoichi Miyahara

Peter Grutter
title: Implementation of atomically defined field ion microscopy tips in scanning probe microscopy.
venue: Nanotechnology
year: 2012

abstract: We perform detailed numerical simulations of field ion microscopy images of faceted crystals and compare them with experimental observations. In contrast to the case of crystals with a smooth surface, for a faceted topography we find extreme deformations of the ion image. Local magnification is highly inhomogeneous and may vary by an order of magnitude: from 0.64 to 6.7. Moreover, the anisotropy of the magnification at a point located on the facet edge may reach a factor of 10.
author_names: Daniel Niewieczerzal

Czeslaw Oleksy

Andrzej Szczepkowicz
title: Image deformation in field ion microscopy of faceted crystals.
venue: Ultramicroscopy
year: 2010

abstract: Field ion microscopic imaging of monatomic carbon chains near the ground quantum states and the visualization of their two dimensional wave functions were demonstrated. Quantum motions with the frequency proportional to the electric field are detected and analyzed with subangstrom lateral resolution. Electric fields above 10(10) V/m can be used for control of a transverse vibration mode of atomic chains in the terahertz spectral range.
author_names: Tatjana I Mazilova

Igor M Mikhailovskij

V A Ksenofontov

Evgenij Sadanov
title: Field ion microscopy of quantum oscillations of linear carbon atomic chains.
venue: Nano letters
year: 2009

abstract: 1. Historical background and general introduction 2. Physical principles of field ion microscopy 3. FIM image interpretation and application 4. Physical principles of atom probe interpretation 5. Statistical analysis of atom probe data 6. Metallurgical applications 7. Atom probe studies of non metallic materials, thin films and surface phenomena Epilogue: future directions
author_names: Michael K Miller
title: Atom Probe Field Ion Microscopy
year: 1996

abstract: The Helium Ion Microscope (HIM) has the capability to image small features with a resolution down to 0.35 nm due to its highly focused gas field ionization source and its small beam sample interaction volume. In this work, the focused helium ion beam of a HIM is utilized to create nanopores with diameters down to 1.3 nm. It will be demonstrated that nanopores can be milled into silicon nitride, carbon nanomembranes (CNMs) and graphene with well defined aspect ratio. To image and characterize the produced nanopores, helium ion microscopy and high resolution scanning transmission electron microscopy were used. The analysis of the nanopore's growth behavior, allows inferring on the profile of the helium ion beam.
author_names: Daniel Emmrich

Andreas Beyer

Achim Nadzeyka

Sven Bauerdick

J C Meyer

Jani Kotakoski

Armin Golzhauser
title: Nanopore fabrication and characterization by helium ion microscopy
year: 2016

abstract: On October 11, 1955, Muller and Bahadur Pennsylvania State University observed individual tungsten atoms on the surface of a sharply pointed tungsten tip by cooling it to 78 K and employing helium as the imaging gas. Muller and Bahadur were the first persons to observe directly individual atoms, using a field ion microscope FIM which Muller had invented in 1951. This historic and seminal event occurred long before the observations of individual atoms by Z contrast scanning transmission electron microscopy STEM high resolution electron microscopy HREM scanning tunneling microscopy STM or atomic force microscopy AFM A FIM is a lensless point projection microscope that resolves individual atoms on the surface of a sharply pointed tip at magnifications of greater than 106 times. The radius of a tip is 50 nm and is maintained at a positive potential Vdc with respect to earth. Atomic resolution FIM images are achieved by cooling a tip into the range of 20 100 K in a high to ultrahigh vacuum system and placing it at Vdc to generate electric fields E that are between 15 and 60 V nm 1. Helium or neon gas, or a mixture of He and Ne gases, is used to image individual atoms utilizing the phenomenon of field ionization. In these large E fields He or Ne atoms are field ionized, 45 Vdc nm 1 for He and 35 Vdc nm 1 for Ne, above individual surface atoms. This is because the outermost electron of the imaging gas atoms quantum mechanically tunnels into a sharply pointed microtip at the site of an atom. This creates a small diameter cone of He+ or Ne+ ions emanating from individual surface atoms; the total current from a tip with an area of 10 14 m2 is 10 9 10 8 A, hence the current from a single atom is 10 14 10 13 A, respectively. The field ionized He+ or Ne+ ions are then accelerated along E field lines that are orthogonal to the equipotentials associated with a tip and they terminate on a detector, which is at earth potential. The energetic ions are ultimately converted into visible light employing a microchannel plate MCP which is the solidstate analog of an array of photomultiplier tubes, with a gain of 106 107 for a single ion. The detection efficiency of a MCP is equal to its open area, 50% 60% which is a weak link in the detection system and needs to be improved in the future. In the FIM mode of operation, about 104 105 surface atoms are imaged and the FIM images often exhibit the symmetry of the crystal lattice of the specimen. Thus, the physical basis of "seeing" atoms in direct space involves the quantum mechanical process of field ionization of imaging gas atoms, which was first analyzed by Oppenheimer 1928 5 for a hydrogen atom in free space in a potential gradient of 102 Vdc m 1; he calculated the time to ionize an atom at this value of E to be 10100 s, which is a googol, whereas in a FIM the time for field ionization is 10 10 s. The E field ionized He+ or Ne+ gas ions are the messengers that allow us to observe individual atoms on the surface of a sharply pointed specimen in direct space with excellent atomic resolution, which is a singular intellectual and scientific achievement with tremendous ramifications for solving important scientific and technological problems in materials research. Subsequently in 1956, Muller discovered the important physical phenomenon of field evaporation or field desorption which is the sublimation of atoms as ions from a microtip radius 40 nm specimen employing a high E field that may be greater or less than the E field necessary to ionize a helium or neon atom at a given cryogenic temperature. Muller observed this phenomenon occurring by increasing the dc voltage on a tungsten specimen, and concomitantly increasing the value of E, and noticing that the atoms at the surface of a microtip are continuously "evaporating subliming " as ions, thereby exposing the interior of a specimen, and hence the term field desorption or field evaporation. Field evaporation is sublimation with the aid of an electric field and is a material dependent property; for example, for W the evaporation field Ee is 57 V nm 1, while for Ag, Ee is 25 V nm 1 at 0 K. Field evaporation is controlled by superimposing high voltage pulses Vpulse on top of Vdc, where the pulse fraction Vpulse /Vdc is typically between 0.1 and 0.2; the optimum value is found empirically. In this manner the internal atomic structure of a specimen is routinely observed directly and reconstructed in threedimensions 3D to reveal imperfections: that is, atomicscale defects, such as vacancies, self interstitial atoms, chemical impurity atoms, dislocations, stacking faults, sub boundaries, grain boundaries, clusters of atoms, precipitates, etc. A historic and seminal short course and workshop on FIM was held at the University of Florida in March 14 22, 1966. Review and original articles were presented on both the theory and application of FIM to problems in materials REVIEW OF SCIENTIFIC INSTRUMENTS 78, 030901 2007
author_names: David N Seidman
title: Perspective: From field ion microscopy of single atoms to atom probe tomography: A journey: "Atom probe tomography" [Rev. Sci. Instrum. 78, 031101 (2007)
venue: The Review of scientific instruments
year: 2007