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Direct write with a liquid precursor using an ion beam in situ, allows fabrication of nanostructures with higher purity than using gas phase deposition. Specifically, positively charged helium ions, when compared to electrons, localize the reaction zone to a single-digit nanometer scale. However, to control the interaction of the ion beam with the liquid precursor, as well as enable single digit fabrication, a comprehensive understanding of the radiolytic process, and the role of secondary electrons has to be developed. Here, we demonstrate an approach for directly writing platinum nanostructures from aqueous solution using a helium ion microscope, and discuss possible mechanisms for the beam-induced particle growth in the framework of Born-Oppenheimer and real-time electron dynamics models. We illustrate the nanoparticle nucleation and growth parameters through data analysis of in situ acquired movie data, and correlate these results to a fully encompassing, time-dependent, quantum dynamical simulation that takes into account both quantum and classical interactions. Finally, sub-15 nm resolution platinum structures generated in liquid are demonstrated.

Serial block-face electron microscopy (SBEM) provides nanoscale 3D ultrastructure of embedded and stained cells and tissues in volumes of up to 107 µm3. In SBEM, electrons with 1–3 keV energies are incident on a specimen block, from which backscattered electron (BSE) images are collected with x, y resolution of 5–10 nm in the block-face plane, and successive layers are removed by an in situ ultramicrotome. Spatial resolution along the z-direction, however, is limited to around 25 nm by the minimum cutting thickness. To improve the z-resolution, we have extracted depth information from BSE images acquired at dual primary beam energies, using Monte Carlo simulations of electron scattering. The relationship between depth of stain and ratio of dual-energy BSE intensities enables us to determine 3D structure with a ×2 improvement in z-resolution. We demonstrate the technique by sub-slice imaging of hepatocyte membranes in liver tissue.

Information in SEM images about specimen properties is conveyed when contrast in the backscattered and/or secondary electron signals is created by differences in the interaction of the beam electrons between a specimen feature and its surroundings. The resulting differences in the backscattered and secondary electron signals (S) convey information about specimen properties through a variety of contrast mechanisms. Contrast (Ctr) is defined as $$ {C}_{\mathrm{tr}}=\left({S}_{\mathrm{max}}-{S}_{\mathrm{min}}\right)/{S}_{\mathrm{max}} $$ where is Smax is the larger of the signals. By this definition, 0 ≤ Ctr ≤ 1.

By selecting the operating parameters of the SEM electron gun, lenses, and apertures, the microscopist controls the characteristics of the focused beam that reaches the specimen surface: energy (typically selected in the range 0.1–30 keV), diameter (0.5 nm to 1 μm or larger), beam current (1 pA to 1 μA), and convergence angle (semi-cone angle 0.001–0.05 rad). In a conventional high vacuum SEM (typically with the column and specimen chamber pressures reduced below 10−3 Pa), the residual atom density is so low that the beam electrons are statistically unlikely to encounter any atoms of the residual gas along the flight path from the electron source to the specimen, a distance of approximately 25 cm.

While amorphous substances such as glass are encountered both in natural and artificial materials, most inorganic materials are found to be crystalline on some scale, ranging from sub-nanometer to centimeter or larger. A crystal consists of a regular arrangement of atoms, the so-called «unit cell,» which is repeated in a two- or three-dimensional pattern. In the previous discussion of electron beam–specimen interactions, the crystal structure of the target was not considered as a variable in the electron range equation or in the Monte Carlo electron trajectory simulation. To a first order, the crystal structure does not have a strong effect on the electron–specimen interactions. However, through the phenomenon of channeling of charged particles through the crystal lattice, crystal orientation can cause small perturbations in the total electron backscattering coefficient that can be utilized to image crystallographic microstructure through the mechanism designated «electron channeling contrast,» also referred to as «orientation contrast» (Newbury et al. 1986). The characteristics of a crystal (e.g., interplanar angles and spacings) and its relative orientation can be determined through diffraction of the high-energy backscattered electrons (BSE) to form «electron backscatter diffraction patterns (EBSD).

A conducting or semiconducting specimen must maintain good contact with electrical ground to dissipate the injected beam current. Without such an electrical path, even a highly conducting specimen such as a metal will show charging artifacts, in the extreme case acting as an electron mirror and reflecting the beam off the specimen. A typical strategy is to use an adhesive such as double-sided conducting tape to both grip the specimen to a support, for example, a stub or a planchet, as well as to make the necessary electrical path connection. Note that some adhesives may only be suitable for low magnification (scanned field dimensions greater than 100 × 100 μm, nominally less than 1,000× magnification) and intermediate magnification (scanned field dimensions between 100 μm x 100 μm, nominally less than 1,000X magnification and 10 μm × 10 μm, nominally less than 10,000× magnification) due to dimensional changes which may occur as the adhesive outgases in the SEM leading to image instability such as drift. Good practice is to adequately outgas the mounted specimen in the SEM airlock or a separate vacuum system to minimize contamination in the SEM as well as to minimize further dimensional shrinkage. Note that some adhesive media are also subject to dimensional change due to electron radiation damage during imaging, which can also lead to image drift.

The incident beam energy is one of the most useful parameters over which the microscopist has control because it determines the lateral and depth sampling of the specimen properties by the critical imaging signals. The Kanaya–Okayama electron range varies strongly with the incident beam energy: $$ {R}_{K-O}(nm)=\left(27.6\ A/{Z}^{0.89}\rho \right){E_0}^{1.67} $$ where A is the atomic weight (g/mol), Z is the atomic number, ρ is the density (g/cm3), and E0 (keV) is the incident beam energy, which is shown graphically in Fig. 11.1a–c.

While X-ray analysis can be performed in the Variable Pressure Scanning Electron Microscope (VPSEM), it is not possible to perform uncompromised electron-excited X-ray microanalysis. The measured EDS spectrum is inevitably degraded by the effects of electron scattering with the atoms of the environmental gas in the specimen chamber before the beam reaches the specimen. The spectrum is always a composite of X-rays generated by the unscattered electrons that remain in the focused beam and strike the intended target mixed with X-rays generated by the gas-scattered electrons that land elsewhere, micrometers to millimeters from the microscopic target of interest.

The scanning electron microscope (SEM) has become the most widely used of all advanced imaging tools because it offers a unique range of capabilities. It can resolve and image objects with sizes ranging from millimeters to below 1 nm; it offers multiple ways to generate, collect, and display signals; the images produced contain information about the topography, chemical composition, and the magnetic, electrostatic, and crystallographic properties of the sample; and it can generate characteristic x-ray emission from the specimen to provide a quantitative chemical analysis. Unfortunately, one thing that it will be unable to do is maintain its competitive edge in the 21st century. This is because electrons are electromagnetic ‘‘waves’’ and thus the smallest spot, ‘‘d,’’ into which an electron beam can be focused has a diameter of the order of: d 1⁄4 k=a ð1Þ

The absolute efficiency of X-ray production has been determined for the K-lines of Al, Si and Cu; for the L-lines of Fe, Co, Cu, Ge and As; and for the M-lines of Hf, Ir, Pt, Au and Bi, using overvoltage ratios in the range 1-10. These emissions, with the exception of the Cu K, have critical excitation energies below 2.6 keV and are therefore typical of the lines used for X-ray microanalysis at low beam energies. For K-lines it is found that the experimental results are in good agreement with a Bethe, or a Casnati, crosssection model. For the L- and M-lines a Monte Carlo technique has been used to find an effective X-ray generation cross-section for each of the elements. The functional forms of these cross-sections are found to be in general agreement with proposed theoretical models.

A formula is presented for computing the polar angle of collisions from partial elastic Mott cross-sections. It will be useful in Monte Carlo simulations of electrons' trajectories in solids and is based on the Newbury and Myklebust (1981) expression. It also is valid for all energy ranging from 0.1 to 30 keV. Also given is the tabulation of the constants of this formula to compute polar angles of collisions for the first 94 elements of the periodic table. The constants of this formula have been obtained by the numerical integration of the values of partial Mott cross-sections computed by Czyzewski et al. (1990) using Thomas-Fermi-Dirac atomic potentials for atomic numbers >54 and Hartree-fock potential for atomic numbers

Monte Carlo modeling of electron-solid interactions requires a detailed and accurate supply of experimental data on which to base its physics and against which to test its predictions. To meet this need, a collection of data—comprising measurements of secondary and backscattered electron yields, electron stopping powers, and x-ray ionization cross sections, as a function of energy—has been assembled from published sources. The quality and quantity of the compilation varies widely, with little or no data being available for the majority of elements in the periodic table, while results for complex materials of current technologic interest are also almost nonexistent. To meet the needs of Monte Carlo simulation in areas such as dimensional metrology or microanalysis, a program of systematic measurements is required.

A study of the temperature dependence of the electron beam induced deposition (EBID) of tungsten was carried out in a temperature range of −30–75°C under two conditions of beam energy and beam current using WF6 as the precursor gas. An Arrhenius relationship was found for the temperature dependence of the deposition rate which is consistent with an electron stimulated desorption mechanism for this process. In addition, the mechanism for EBID under different conditions was discussed.

Low voltage scanning electron microscopy (LVSEM) has become the imaging technique of choice for many applications because it offers surface specific information, and both control of charging and a reduction of damage to labile specimens. However fundamental limitations such as the electron wavelength, lens aberrations, and gun brightness, severely limit the performance of the LVSEM, and in addition some capabilities such as microanalysis are difficult or impossible. New technologies, including aberration correction and brighter electron sources are now available, and novel spectroscopic approaches are in development. Together these advances could significantly enhance the performance of the LVSEM. The advent of ultra-high performance ion column imaging systems offers interesting competition to the LVSEM for both imaging and analysis. [DOI: 10.1380/ejssnt.2006.369]

Specimens that charge under electron beam irradiation in the scanning electron microscope (SEM) can be stabilized by choosing the beam energy to be such a value that the sum of the secondary and backscatter electron yields is unity, as this establishes a dynamic charge balance. We show here that for pure elements, the energies El and E2, for which charge balance occurs, are related directly to the atomic number of the material. Although generally there is no comparable relation for compounds, we also show that for polymers, the E2 energy is related both to the ratio of the number of valence electrons to molecular weight and to the electro-negativity of the monomer units that form the polymer.

The scanning electron microscope (SEM) has become the most widely used high-performance microscope. However because of the fundamental limitations of electron beams the new technology of ion beam microscopy is being developed

Both electron and ion beams can be used to provide a number of different modes of imaging and microanalysis In every case, and in order to properly optimize and interpret the data generated by the instrument, it is necessary to know something about what kinds of beam interactions are involved, what information may be obtained from each, and how the signal yields and spatial resolution can be optimized in each case. Images whose origins are neither known nor understood can never be any more than just a pretty picture.

It has to be expected that both ions and electrons will damage specimens under examination to a greater or lesser degree. Electrons are low in mass but can travel at velocities which are a significant fraction of the speed of light. In general, electrons do not significantly damage metallic or inorganic specimens, but even relatively low doses of electrons can be expected to chemically alter or destroy organic materials such as polymers and biological samples.

In this paper we will discuss our recent experimental results, using electron holography and electron interferometry, of studies of ferroelectric domain walls in BaTiO3 and PLZT thin specimens.

An electron holographic method is introduced for the study of ferroelectric domain walls. The method allows not only direct imaging of the domain wall but also the measurement of local spontaneous polarization. Preliminary results of first high-resolution imaging of ferroelectric domain walls by using this technique in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls are presented.

IONiSE is a Monte Carlo simulation which describes the interactions of 5-50 keV energy He+ ions with solids, and predicts the production of ion induced secondary electron (iSE) emission. Its use to determine the most probable implant depth, the maximum ion range, and the effect of straggle are presented. IONiSE has been used to numerically fit literature tabulations of iSE generation from five elements so as to derive excitation energy and mean free path parameters. By employing those parameters in IONiSE the topographic yield variation for iSE as a function of energy and the atomic number of the target has been predicted, and estimates of the individual secondary electron contributions from the incident and backscattered ions have been made. These simulations help to create a foundation for the application and the interpretation of iSE images for metrology.

Electron-beam-induced deposition (EBID) and etching (EBIE) provides a simple way to fabricate or etch submicron or nanoscale structures of various materials in a direct-write (i.e.nonlithographic) fashion. The growth rate or the etch rate are influenced by many factors such as beam energy, beam current, temperature of the substrate material, pressure of the chamber, and geometry of the gas injector etc. The mechanism of EBID and EBIE involves the interaction of the incident electron beam or emitted electron from the target material. The role of these electrons is still not completely understood although the contribution of low energy secondary electrons (SE) has been assumed to be the dominant contributor of EBID and EBIE based on its overlap with the dissociation cross section. We have studied the growth and etching phenomenon under various biasing conditions to investigate how low voltage biasing of the substrate affects secondary electron trajectories and subsequently modifies electron-beam-induced deposition and etching.SCANNING 29: 000–000, 2007. © 2007 Wiley Periodicals, Inc.

Although electron beams with energies of a few keV can excite fluorescent X-ray production from solids, ion beams of comparable energy cannot do so. The reason for this situation is that it is the velocity of the incident particle, rather than its energy, which determines whether an ionization event can be generated. SCANNING 29: 1–4, 2007. Copyright © 2007 Wiley Periodicals, Inc.

The monoatomic hydride layer on silicon was used as a prototype for resistless electron beam lithography. Arbitrary patterns with linewidths below 60 nm have been achieved. The variation of the linewidth with electron energy, electron dose, and substrate thickness was studied to determine the mechanisms that govern surface hydrogen desorption and subsequent pattern formation. Unlike in resist based lithography, no resolution enhancement was observed with decreasing substrate thickness. The experimental data in combination with Monte Carlo simulations of the backscattered and transmitted electrons suggest that surface hydrogen desorption and pattern formation are not strongly related to the backscattered electrons and the secondary electrons (energies

Summary The electron backscattering coefficient of liquid water has been determined for electrons in the energy range 15–30 keV using QuantomixTM capsules. Values of the mean atomic number for water estimated from a fit to the backscatter yield, the mean ionization potential of water and from Monte Carlo simulations, show that the scattering behaviour of water is not anomalous despite the effects of hydrogen bonding. Computations of the electron range, and of the mean depth for backscattering, in water as a function of incident beam energy show that water and vitreous ice are good media for imaging purposes.

Because a photomask is typically a block of quartz partially covered a thin metal coating it charges significantly under an electron beam making CD metrology difficult and often imprecise. A solution to this problem can be found by performing the measurement in the presence of a low pressure of gas in a variable pressure scanning electron microscope (VPSEM). The gas is ionized by the emitted secondary electrons so producing both positive and negative ions which drift to the charged surface and neutralize it. This process is self controlling and requires no critical adjustments by the operator. With charging removed metrology can then be performed over a wide range of beam energies using either secondary or backscattered electron signals with excellent precision and accuracy. The presence of the gas atmosphere also eliminates beam induced contamination effects. If a chemically active precursor gas is injected into the system then the electron beam can also be used to edit and repair damaged masks.

Electron-beam-stimulated etching has been investigated as a clean, alternative method for nanoscale selective processing. Primarily fluorine-based precursors have been used to etch a variety of technologically relevant materials. Empirical data reveals that with decreasing the electron beam energy increases the material removal rate, however the effective beam width increases. Both of these observations are consistent with the fact that cross-sections for electron-gas scattering increases with decresaing beam energy. Monte Carlo models of the electron-gas and electron-solid interactions have been performed to better udnerstand the fundamentals of the process. Finally, specific application to soft transmission electron microscopy sample preparation is made.

Voltage profiles of the source-drain region of a CMOS transistor with 75nm gate architecture taken from an off-the-shelf Intel PIII processor are presented. The sample preparation using a dual beam system is discussed as well as details of the electron optical setup of the microscope. Special attention is given to the analysis of the reconstructed holograms.

Chapter 9 presented the procedures for performing quantitative electron probe x-ray microanalysis for the casef an ideal specimen. The ideal specimen surface is flat and highly polished to reduce surface roughness to a negligible level so that electron and x-ray interactions are unaffected by geometric effects. Such a highly polished surface has a short-range surface topography (sampled at distances less than 1 μm) that is reduced to an amplitude of a few nanometers and the long-range topography (sampled at distances greater than 100 μm) that is reduced to 100 nm or less. These ideal specimens satisfy three “zeroth” assumptions that underlie the conventional EPMA technique: 1. The only reason that the x-ray intensities measured on the unknown differ from those measured on the standards is that the compositions of specimen and standard are different. Specifically, no other factors such as surface roughness, size, shape, and thickness, which can be generally grouped together as “geometric” factors, act to affect the intensities measured on the unknown. 2. The specimen is homogeneous over the full extent of the interaction volume excited by the primary electron beam and sampled by the primary and secondary x-rays. Because x-rays of different excitation energies are generated with different distributions within the interaction volume, it is critical that the specimen has a uniform composition over the full region. If a thin surface layer of different composition than the underlying bulk material is present, this discontinuity is not properly considered in the conventional matrix correction analysis procedure. 3. The specimen is stable under the electron beam. That is, the interaction volume is not modified through loss of one or more atomic or molecular species by the electron beam over the time period necessary to collect the x-ray spectrum (EDS) or peak intensities (WDS). Biological and polymer specimens are likely to alter composition under electron bombardment.

Obtaining a low-magnification (

The specimen can be thought of as an electrical junction into which flows the beam current i B. The phenomena of backscattering of the beam electrons and secondary electron emission represent currents flowing out of the junction, i BSE and i SE, respectively. For a copper target with an incident beam energy of 20 keV, η is approximately 0.3 and δ is approximately 0.1, which accounts for 0.4, or 40%, of the beam current. The remaining beam current must flow from the specimen to ground to avoid the accumulation of charge in the junction (Thevenin’s current theorem). The balance of the currents is then given by $$ \eqalign{ & \sum {{i_{in}}} = \sum {{i_{out}}} \cr & {\rm{ }}{i_B} = {i_{BSE}} + {i_{SE}} + {i_{SC}}, \cr} $$ (15.1) where i SC is the specimen (or absorbed) current. For the example of copper, i SC = 0.6i B. Thus, even with a conducting specimen such as a metal, an electrical connection must be established to conduct this substantial current from the specimen to ground (typically the specimen stage is wellgrounded). Because all materials (except superconductors) have the property of electrical resistivity ρ, the specimen has a resistance R ( R = ρ l / A, where l is the length of the specimen and A is the cross section). The passage of the specimen current i SC through this resistance will cause a potential drop across the specimen, V = i SC R. For a metal, ρ is typically of the order of 10-6 ohm-cm, so that a specimen 1 cm thick with a crosssectional area of 1 cm2 will have a resistance of 10-6 ohm, and a beam current of 1 nA (10-9 A) will cause a negligible potential of about 10-15 V to develop across the specimen.

We show simulation images of projection microscope, which uses parallel beam to the sample, detecting secondary electrons, photoelectrons and mirror electrons using electrons and UV/X-ray sources as probe beam. The results show we can see image for square and dense line patterns without charging and damage in the objects. This research can be used for quantitative analysis for projection microscope using multi beam source to get comprehensive information of many characteristics of objects as well as topographic information.

Charging effects on secondary electron (SE) profiles with bias voltage in deep contact holes are investigated. We show first in detail the SE beam profiles for operating conditions such as scanning time, current and landing energy, the brightness of the bottom of the contact hole depends on the charge of SE yield with incident energy. We conclude that we can enhance the contrast of the beam profile by optimizing the applied bias voltage.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Electron holography performed in a transmission electron microscope, has been used to measure the width of 90° domain walls in tetragonal BaTiO3, and to determine the magnitude and distribution of the polarization across these walls. The walls are found to be between 15 and 25 A in width. The polarization and its measured variation are in good agreement with other estimates. Fringe splitting has been observed in some holograms and it is suggested that this is due to the presence of charged oxygen vacancies on the walls.

The charging of the workpiece in electron beam direct writing processes has been identified as a problem that disturbs the electron beam and causes pattern displacement error. In this paper the electron beam deflection caused by surface charging is evaluated by the SIMION and MATHEMATICA simulation programs. Isolated charged patterns of different geometry are simulated as electrodes with given potentials in SIMION to calculate the extent of beam deflection, while secondary electron emission yield and beam dosage are assigned in MATHEMATICA programming for determination of surface potential and spatial field, from which the beam deflection is then calculated. The simulation results are in good agreement with each other and they are compared with values available in literature. The initial charge content along with the pattern dimensions chosen in simulation are found to be the major factors that determine the extent of beam deflection. The limitation of SIMION simulation on the beam deflection is also discussed.

Charging effects on beam deflection of incident electrons in electron beam lithography are investigated. We show first in detail how the non-unity yield of electron generation in insulator resists leads to local charging accumulation and affects the beam deflection of incident electrons as charging develops. Then the amounts of beam deflection are identified for various operating and resist dimension conditions, and then we conclude that the beam deflection should be avoided for more accurate manufacturing semiconductor devices by the control of charging effects.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

The charging of polymeric resist materials during electron beam irradiation leads to significant problems during imaging and lithography processes. Charging occurs because of charge deposition in the polymer and charge generation/trapping due to formation of electron-hole pairs in the dielectric. The presence of such charge also results in the phenomena of electron beam-induced conductivity (EBIC). Electron beam-induced conductivity data have been obtained for three commercial e-beam resists under a variety of dose rate and temperature conditions. From the observed values of induced conductivity under varying conditions significant information about the generation of electron-hole pair and the transport of charge in the resist can be obtained. Three electron beam resists, EBR900, ZEP7000, and PBS are examined by an external bias method. The difference in resist chemistry is considered to play the role in the initial state EBIC behaviors among three resists even though the way that it affects the behaviors is not clear. A comparison of the power consumption comparison is proposed as a measure to give a preliminary estimate of the carrier concentration and carrier drift velocity differences among the resists. A simple single trap model with constant activation energy is proposed and provides good agreement with experiment.

Valid Conventions throughout the Book. 1. The History of the Electron Biprism. 2. Principles and Theory of Electron Holography. 3. Optical Characteristics of a Holography Electron Microscope. 4. Practical Electron Holography. 5. Quantitative Electron Holography. 6. The Reconstruction of Off-Axis Electron Holograms. 7. Electron Holography of Electromagnetic Fields. 8. On Recording, Processing and Interpretation of Low Magnification Electron Holograms. 9. High Resolution Off-Axis Electron Holography. 10. Off-Axis Stem Holography. 11. Focus Variation Electron Holography. 12. Applications of Electron Holography. 13. Electron Holography using Diffracted Electron Beams (DBH). 14. Electron Holography at Low Energy. 15. A Plus or Minus Sign in the Fourier Transform? Bibliography. Index.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

The details of a Monte Carlo helium ion beam induced deposition simulation are introduced and initial results for reaction rate and mass transport limited growth regimes are presented. Reaction rate limited growth leads to fast vertical growth from incident primary ions and minimal lateral broadening, whereas mass transport limited growth has lower vertical growth velocity and exhibits broadening due to scattered ions and secondary electrons. The results are compared to recent experiments and previous electron beam induced deposition simulations.

The spatial resolution of the scanning electron microscope is limited by at least three factors: the diameter of the electron probe, the size and shape of the beam/specimen interaction volume with the solid for the mode of imaging employed and the Poisson statistics of the detected signal. Any practical consideration of the high-resolution performance of the SEM must therefore also involve a knowledge of the contrast available from the signal producing the image and the radiation sensitivity of the specimen. With state-of-the-art electron optics, resolutions of the order of 1 nm are now possible. The optimum conditions for achieving such performance with the minimum radiation damage to the specimen correspond to beam energies in the range 1-3 keV. Progress beyond this level may be restricted by the delocalization of SE production and ultimate limits to electron-optical performance.

Nonconducting samples invariably need some sort of treatment before they can be examined and analyzed under optimal conditions in electron-beam instruments that rely on an emitted signal to provide information. The treatment is necessary to eliminate or reduce the electric charge that builds up rapidly in a nonconducting specimen when it is scanned by a beam of high-energy electrons. Figs. 4.63a–c and 4.64a–c show examples of pronounced and minor charging as observed in the SEM. In addition to charging phenomena, which result in image distortion, the primary beam also causes thermal and radiation damage, which can lead to a significant loss of material from the specimen. In many situations the specimen may acquire a sufficiently high charge to decelerate the primary beam, and the specimen may even ultimately act as an electron mirror (see Fig. 4.62).

The versatility of scanning electron microscopy and of x-ray micro-analysis is derived in large measure from the rich variety of interactions that the beam electrons undergo in a specimen. These interactions can reveal information on the specimen’s composition, topog­raphy, crystallography, electrical potential, local magnetic field, and other properties. The electron—specimen interactions can be divided into two classes.

In this paper we will present recent experimental results, using electron holography and electron interferometry, of studies of ferroelectric domain walls in BaTiO3 thin films. Unlike conventional TEM diffraction contrast imaging of ferroelectrics, the new technique that we have developed not only allows direct visualization of ferroelectric domain walls and electrostatic field distributions in the vicinity of the domain wall, but also enables quantitative measurement of domain wall width and local polarization. We have measured 90° domain wall width to be between 20 to 50 Å for a BaTiO3 thin specimen. The variation of polarization across the domain wall will be shown to be close to that predicted by the Zhirnov model. The value of the measured spontaneous polarization is about 1.5×10−5 C/cm2, which is closed to the bulk macroscopically measured value.

The development of quantitative X-ray microanalysis in the 1950s spurred the need for knowledge of the many parameters which describe the electron interaction, such as the ionization cross-sections, fluorescent yields, the electron stopping power, mass absorption coefficients, and others. Although classical microanalysis, which proceeds by measurements of the unknown specimen against a standard, can eliminate the need to know many of these parameters accurately, much current microanalysis is done on highly inhomogeneous samples for which comparison with a standard is much less useful procedure. The increased use of low beam energies also means that data is now required for L-, and M-lines which previously have been little used. Consequently there is an enhanced need for a reliable and agreed set of data on which to base calculations.A common misconception is the belief that all of the quantities that are needed must already have been measured by somebody and so it is simply a matter of accessing this data.

The purpose of this laboratory is to prepare samples of metals, ceramics, and geological and microelectronic specimens for examination and analysis in the transmission electron microscope (TEM) and analytical electron microscope (AEM). Material forms include bulk, thin films, and particles. To achieve suitable electron transparency, and meet various requirements for electron diffraction and microanalysis, the thin region of the specimen must be

The theory of imaging crystallographic defects in solid specimens through the use of electron channeling contrast is reviewed and the necessary conditions for observation are deduced. It is shown that current high performance field emission scanning electron microscopes can meet these requirements and produce dislocation images from suitable materials.