Rapid determination of local composition in quasi-binary, inhomogeneous material systems from backscattered electron image contrast

The present work concerns the back-scattered electron image contrast of a thin film of Cu64Mo36 on a silicon substrate. The contrast is defined by the ratio(1)where If and Ib are the backscattered electron signals from the film and from an adjacent bulk reference specimen. In previous work on thin sputtered films of Cu-Mo, Cu-W and Cu-Al both the film and the bulk reference specimen were perpendicular to the incident electron beam. It was found that the dependence of r on the accelerating voltage of the electron beam could be used to obtain both the thickness and the composition of the films. It is the purpose of the present work to determine whether the simple method previously used to extract the required information can be extended to include tilted specimens. As will be seen the method can be adapted to films tilted by less than 50°.

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A simple method for the determination of film thickness from electron image contrast in a scanning electron microscope

Thin Solid Films ◽

10.1016/0040-6090(85)90163-4 ◽

1985 ◽

Vol 123 (3) ◽

pp. 235-238 ◽

Cited By ~ 14

Author(s):

O.S. Rajora ◽

A.E. Curzon

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Film Thickness ◽

Image Contrast ◽

Simple Method ◽

Electron Image ◽

Scanning Electron

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Weak Beam Imaging and Diffraction Studies of Stacking Faults in Silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092918 ◽

1976 ◽

Vol 34 ◽

pp. 590-591

Author(s):

T. Y. Tan ◽

W. K. Tice

Keyword(s):

Fast Neutron ◽

Rapid Determination ◽

Stacking Faults ◽

Imaging Method ◽

Large Reduction ◽

Dislocation Loops ◽

Fringe Spacing ◽

Weak Beam ◽

Kinematical Theory

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.

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Contrast in Scanning Images of Thin Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095856 ◽

1972 ◽

Vol 30 ◽

pp. 520-521

Author(s):

S. Kimoto ◽

H. Hashimoto ◽

S. Takashima ◽

R. M. Stern ◽

T. Ichinokawa

Keyword(s):

Crystal Surface ◽

Solid Angle ◽

Incident Angle ◽

Intensity Variation ◽

Lattice Defects ◽

Scanning Microscope ◽

Electron Detector ◽

Backscattered Electrons ◽

Electron Image ◽

Backscattered Electron

The most well known application of the scanning microscope to the crystals is known as Coates pattern. The contrast of this image depends on the variation of the incident angle of the beam to the crystal surface. The defect in the crystal surface causes to make contrast in normal scanning image with constant incident angle. The intensity variation of the backscattered electrons in the scanning microscopy was calculated for the defect in the crystals by Clarke and Howie. Clarke also observed the defect using a scanning microscope.This paper reports the observation of lattice defects appears in thin crystals through backscattered, secondary and transmitted electron image. As a backscattered electron detector, a p-n junction detector of 0.9 π solid angle has been prepared for JSM-50A. The gain of the detector itself is 1.2 x 104 at 50 kV and the gain of additional AC amplifier using band width 100 Hz ∼ 10 kHz is 106.

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Preparation And elemental analysis of ancient fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126846 ◽

1987 ◽

Vol 45 ◽

pp. 410-411

Author(s):

Allen Angel ◽

Kathryn A. Jakes

Keyword(s):

Cross Sections ◽

Physical Structure ◽

Energy Dispersive ◽

Archaeological Sites ◽

X Ray ◽

Long Term Storage ◽

Backscattered Electron ◽

Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

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Problems in Thin-Film X-ray Quantification

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135897 ◽

1990 ◽

Vol 48 (2) ◽

pp. 458-459

Author(s):

J N Chapman ◽

W A P Nicholson

Keyword(s):

Thin Film ◽

Specimen Thickness ◽

X Rays ◽

Characteristic Peak ◽

Local Composition ◽

X Ray ◽

Measured Ratio ◽

Path Lengths ◽

Composition Changes

Energy dispersive x-ray microanalysis (EDX) is widely used for the quantitative determination of local composition in thin film specimens. Extraction of quantitative data is usually accomplished by relating the ratio of the number of atoms of two species A and B in the volume excited by the electron beam (nA/nB) to the corresponding ratio of detected characteristic photons (NA/NB) through the use of a k-factor. This leads to an expression of the form nA/nB = kAB NA/NB where kAB is a measure of the relative efficiency with which x-rays are generated and detected from the two species.Errors in thin film x-ray quantification can arise from uncertainties in both NA/NB and kAB. In addition to the inevitable statistical errors, particularly severe problems arise in accurately determining the former if (i) mass loss occurs during spectrum acquisition so that the composition changes as irradiation proceeds, (ii) the characteristic peak from one of the minority components of interest is overlapped by the much larger peak from a majority component, (iii) the measured ratio varies significantly with specimen thickness as a result of electron channeling, or (iv) varying absorption corrections are required due to photons generated at different points having to traverse different path lengths through specimens of irregular and unknown topography on their way to the detector.

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Use of backscattered electron image intensity signals to calculate the water/cement ratio of concrete

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122186 ◽

1992 ◽

Vol 50 (1) ◽

pp. 356-357

Author(s):

R. J. Lee ◽

A. J. Schwoeble ◽

Yuan Jie

Keyword(s):

Reliable Data ◽

X Ray ◽

Rapid Measurement ◽

Trained Personnel ◽

Electron Image ◽

Backscattered Electron ◽

Production Period ◽

Strength And Durability ◽

Automated Procedures ◽

Standard Density

Water/Cement (W/C) ratio is a very important parameter affecting the strength and durability of concrete. At the present time, there are no ASTM methods for determining W/C ratio of concrete structures after the production period. Existing techniques involving thin section standard density comparative associations using light optical microscopy and rely on visual comparisons using standards and require highly trained personnel to produce reliable data. This has led to the exploration of other methods utilizing automated procedures which can offer a precise and rapid measurement of W/C ratio. This paper discusses methods of determining W/C ratio using a scanning electron microscope (SEM) backscattered electron image (BEI) intensity signal and x-ray computer tomography.

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Computer-Assisted High-Re Solution TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179567 ◽

1990 ◽

Vol 48 (1) ◽

pp. 162-163

Author(s):

F.A. Ponce ◽

H. Hikashi

Keyword(s):

Signal To Noise Ratio ◽

Accurate Determination ◽

Computer Software ◽

Video Camera ◽

Image Contrast ◽

Objective Lens ◽

Computer Assisted ◽

Optical Parameters ◽

Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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