Defects at Crystalline Interfaces

1970 ◽  
Vol 28 ◽  
pp. 506-507
Author(s):  
K. R. Kinsman ◽  
H. I. Aaronson
Keyword(s):  
Grain Boundaries ◽  
Single Phase ◽  
Relative Orientation ◽  
Interfacial Structure ◽  
Contrast Effects ◽  
Materials Analysis ◽  
Displacement Vectors ◽  
Transmission Electron ◽  
Line Defects ◽  
Diffraction Effects

Crystalline interfaces are of two basic types - interfaces in single phase solids separating grains of differing orientation (grain boundaries, sub-grain boundaries, twin boundaries), and interphase interfaces separating crystals which differ in crystal structure and/or composition, as well as relative orientation. Depending upon these variables a particular boundary will have more or less interfacial structure which can be resolved by transmission electron microscopy. The dislocations (line defects) which are imaged at boundaries by electron diffraction contrast effects may be unique to the boundary, i.e., have displacement vectors which are different from those of dislocations found in single phase materials. Analysis may be further complicated by extra diffraction effects such as superimposed Moire patterns (Fig. 1a and 2).

The location and effects of Si in (Ti1–xSix)Ny thin films

2009 ◽  
Vol 24 (8) ◽  
pp. 2483-2498 ◽  
Author(s):  
Axel Flink ◽  
Manfred Beckers ◽  
Jacob Sjölén ◽  
Tommy Larsson ◽  
Slawomir Braun ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Photoelectron Spectroscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Arc Evaporation ◽  
Annealing Experiments ◽  
Tissue Phase

(Ti1–xSix)Ny (0 ≤ x ≤ 0.20; 0.99 ≤ y(x) ≤ 1.13) thin films deposited by arc evaporation have been investigated by analytical transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and nanoindentation. Films with x ≤ 0.09 are single-phase cubic (Ti,Si)N solid solutions with a dense columnar microstructure. Films with x > 0.09 have a featherlike microstructure consisting of cubic TiN:Si nanocrystallite bundles separated by metastable SiNz with coherent-to-semicoherent interfaces and a dislocation density of as much as 1014 cm−2 is present. The films exhibit retained composition and hardness between 31 and 42 GPa in annealing experiments to 1000 °C due to segregation of SiNz to the grain boundaries. During annealing at 1100–1200 °C, this tissue phase thickens and transforms to amorphous SiNz. At the same time, Si and N diffuse out of the films via the grain boundaries and TiN recrystallize.

Periodic grain boundary structures in aluminium. II. A geometrical method for analysing periodic grain boundary structure and some related transmission electron microscope observations

1977 ◽  
Vol 357 (1691) ◽  
pp. 471-483 ◽  
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Transmission Electron Microscope ◽  
Boundary Structure ◽  
Geometrical Method ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Line Defects

A crystallographic treatment is developed which clarifies the relation between the structure of a grain boundary and its location between relatively translated crystals. Characterization of line defects which can exist in grain boundaries is also facilitated by using this treatment, and the following topics are considered: (1) the computed structures in part I of this work; (2) steps at the cores of perfect grain boundary dislocations; (3) boundary structures related by c.s.l. symmetry; (4) partial grain boundary dislocations. Transmission electron microscope observations of topic 4 are presented.

The role of Electron Microscopy in the study of grain boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 330-331
Author(s):  
William A. T. Clark
Keyword(s):  
Grain Boundaries ◽  
Optical Microscopy ◽  
Interfacial Structure ◽  
Polycrystalline Materials ◽  
Defect Structures ◽  
General Acceptance ◽  
Transmission Electron ◽  
Ray Methods ◽  
Detailed Picture

Our understanding the nature of interfaces in polycrystalline materials has depended critically on observations obtained in the transmission electron microscope. This is especially true in the case of interfacial structure, where developments in models of atomic and defect structures in interfaces have closely paralleled advances in techniques available for their study. The general acceptance that the crystallography and relative misorientation of the two crystals forming an interface dictate the interfacial structure, and many of its properties, results in large part from direct TEM studies of interfaces.Grain boundaries were originally considered structureless, amorphous, films, because optical microscopy could not provide information at the necessary resolution, and inferences about the nature of boundaries had to be made from measurements of mechanical properties. However, the development of X-ray methods in the 1920's quickly showed that the crystalline structure of the grains was preserved right up to an interface, and that the boundary could be thought of as a “transition lattice” from one crystal to the other, a concept remarkably similar to many of those still current today. Although there was some earlier optical microscopy of decorated low-angle boundaries in Si, it was not until 1956 that the development of the TEM provided the first detailed picture of dislocations and grain boundaries in opaque materials.

Effectiveness of CVD thin Film Backside Gettering and Its Interaction with Intrinsic Gettering

1986 ◽  
Vol 71 ◽  
Author(s):  
C.-C. D. Wong ◽  
S. Hahn ◽  
F. A. Ponce ◽  
Z. U. Rek
Keyword(s):  
Thin Film ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Cmos Technology ◽  
Structure Study ◽  
Interfacial Structure ◽  
Oxide Breakdown ◽  
Transmission Electron ◽  
Line Defects ◽  
Silicon Interface

AbstractThe effectiveness of CVD thin film backside gettering on n-type CZ silicon wafers for CMOS technology has been investigated using optical techniques for bulk microdefect analyses and transmission electron microscopy for interfacial structure study. The deposition of LPCVD polysilicon (500-2000 nm), silicon nitride (150 nm), or poly/nitride films on the backside of Si wafers was found to enhance the bulk precipitation. Bulk microdefect density increased as the thickness of polysilicon increased. At the polysilicon/silicon interface, no extended line defects from polysilicon were observed. Based on the results of minority carrier lifetime and oxide breakdown measurements, the best gettering efficiency was given by 1300 nm polysilicon backside gettering scheme.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Transmission Electron Diffraction Analysis by Computer

1970 ◽  
Vol 28 ◽  
pp. 40-41
Author(s):  
R.A. Ploc ◽  
G.H. Keech
Keyword(s):  
Electron Diffraction ◽  
Input Data ◽  
Reciprocal Lattice ◽  
Computer Programme ◽  
Transmission Electron Diffraction ◽  
Usual Procedure ◽  
Transmission Electron ◽  
Complex Shapes ◽  
Computer Input ◽  
Diffraction Effects

An unambiguous analysis of transmission electron diffraction effects requires two samplings of the reciprocal lattice (RL). However, extracting definitive information from the patterns is difficult even for a general orthorhombic case. The usual procedure has been to deduce the approximate variables controlling the formation of the patterns from qualitative observations. Our present purpose is to illustrate two applications of a computer programme written for the analysis of transmission, selected area diffraction (SAD) patterns; the studies of RL spot shapes and epitaxy.When a specimen contains fine structure the RL spots become complex shapes with extensions in one or more directions. If the number and directions of these extensions can be estimated from an SAD pattern the exact spot shape can be determined by a series of refinements of the computer input data.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Characteristic Geometry and Diffraction Contrast of Dispersed ThO2 Crystals

1969 ◽  
Vol 27 ◽  
pp. 168-169
Author(s):  
R. J. Horylev ◽  
L. E. Murr
Keyword(s):  
Dark Field ◽  
Particle Orientation ◽  
Contrast Effects ◽  
Strain Fields ◽  
Diffraction Contrast ◽  
Dispersed Particles ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Particle Images ◽  
Diffraction Effects

Smith has shown by dark-field electron microscopy of extracted ThO2 particles from TD-nickel (2% ThO2) that they possess single crystal characteristics. It is generally assumed that these particle dispersions are incoherent. However, some diffraction effects associated with the particle images appeared to be similar to coherency strain fields. The present work will demonstrate conclusively that ThO2 dispersed particles in TD-nickel (2% ThO2) and TD-NiCr (2% ThO2, 20% Cr, Ni) are single crystals. Moreover, the diffraction contrast effects are extinction fringes. That is, these effects arise because of the particle orientation with respect to the electron beam and the extinction conditions for various operating reflections The particles are in fact incoherent.

Diffraction effects from inclined grain boundaries in polycrystalline thin foils

1978 ◽  
Vol 36 (1) ◽  
pp. 420-421
Author(s):  
C.B. Carter ◽  
A.M. Donald ◽  
S.L. Sass
Keyword(s):  
Thin Film ◽  
Grain Boundaries ◽  
Boundary Plane ◽  
Foil Surface ◽  
Thin Foils ◽  
The Matrix ◽  
Firm Basis ◽  
Diffraction Patterns ◽  
Wave Matching ◽  
Diffraction Effects

Using thin-film gold bicrystals with the boundary plane parallel to the foil surface, it has been shown(l,2) that networks of grain boundary dislocations can act as diffraction gratings and give rise to subsidiary reflections close to the matrix reflections in electron diffraction patterns. Recently several groups of workers(3-5) have shown that inclined boundaries in polycrystalline specimens also produce extra reflections which may be due to the periodic nature of the boundaries. In general grain boundaries in polycrystalline specimens will be steeply inclined to the foil surface and additional reflections due to wave matching at the boundary(6) will also be present. The diffraction technique has the potential for providing detailed information on the structure of inclined boundaries (see, for example (5)), especially for the case where the image contains no useful information. In order to provide a firm basis for this technique, the geometry of the diffraction effects expected from inclined boundaries and the influence of these effects on the appearance of images will be examined.

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

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