High Resolution Analysis of Structure and Chemistry of Grain Boundaries in Silicon

1991 ◽  
Vol 238 ◽  
Author(s):  
M. J. Kim ◽  
R. W. Carpenter
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Coincident Site Lattice ◽  
Dislocation Core ◽  
Tilt Boundary ◽  
Second Phase ◽  
Twin Boundaries ◽  
Precipitate Morphology

ABSTRACTHigh resolution electron microscopy and high spatial resolution analytical electron microscopy were used to analyze the structure and chemistry of a Σ3 {111} twin boundary in cast polysilicon and a Σ13 (510), [001] tilt boundary in a Si bicrystal. Twin boundaries in cast polysilicon were associated with lattice defects and discrete second phase precipitates. The precipitate was single phase amorphous and faceted on the Si {111} planes. Nanospectroscopy showed mem to be substoichiometric oxide. Similar oxide precipitates, but with different morphology, were also observed on the Σ13 tilt boundary in Si bicrystal, indicating that tilt grain boundaries and steps on twin boundaries were effective heterogeneous sites for nucleation of oxygen containing precipitates. The observed Σ13 tilt boundary exhibited a coincident site lattice periodicity but had an aperiodic interface dislocation core structure. Oxygen that diffused into the boundary in regions where precipitation did not occur may have played a role in modifying the GB core structures, resulting in aperiodicity. For both cases, a detailed analysis of grain boundary atomic structure and precipitate morphology is presented.

New precipitate morphology in heat treated CZ Si wafers

1983 ◽  
Vol 41 ◽  
pp. 152-153
Author(s):  
H.L. TSAI ◽  
R.W. CARPENTER
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
Interstitial Oxygen ◽  
Precipitate Morphology ◽  
Silicon Ingot ◽  
Heat Treated ◽  
Initial Carbon ◽  
Analytical Electron ◽  
Plate Type

The morphological forms of the precipitates and other defects in the heat-treated oxygen-containing CZ silicon have been extensively documented, but little information concerning the morphology as a function of the position in the ingot has been reported. Recent studies, using high resolution analytical electron microscopy, have shown that plate type precipitates observed in the seed end of the silicon ingot were amorphous and contain oxygen. We have carried out a detailed TEM study of the precipitate morphology in the heat-treated wafers cut from the seed, middle, and tang regions of the CZ ingot. The interstitial oxygen concentrations in the as grown Si were 2.1×1018cm−3, 1.6×10−18cm−3, and 1.5×1018cm−3 in the seed, middle and tang regions, respectively. Initial carbon was below IR detectability limit, but was higher in the tail than seed, based on segregation coefficients. The wafers were subjected to two-step anneals: 1. 0-16 hrs., 800°C in nitrogen and 2. 16 hrs., 1050°C in dry oxygen.

A high-resolution EM study of grain boundaries in Pr and Co-doped ZnO ceramics

1993 ◽  
Vol 51 ◽  
pp. 1150-1151
Author(s):  
I.G. Solórzano ◽  
J.B. Vander Sande ◽  
K.K. Baek ◽  
H.L. Tuller
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electrical Activity ◽  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Ionic Radii ◽  
Conventional Sintering ◽  
Doped Zno ◽  
Co Doped

Metal oxide varistors are multijunction materials whose nonlinear current-voltage characteristics derive from the electrical activity of their grain boundary regions. The high degree of nonlinear-ity in polycrystalline ZnO has been attributed to the synergistic action of two types of cations added in sufficient concentrations: transition metals, such as Co and Mn which have ionic radii similar to that of the ZnO matrix, and dopants with large ionic radii, such as Bi and Pr which segregate at grain boundaries and usually form intergranular phases. The present investigation was undertaken with the objective to clarify the role of dopants in an electrically active Pr and Co doped ZnO ceramic by studying the structure and chemistry of individual grain boundaries through high-resolution electron microscopy (HREM) and analytical electron microscopy (AEM).Bulk specimens containing 1 mol% Pr and 1 mol% Co were prepared by conventional sintering at 1400° C. Some samples followed an oxidative anneal at 650° C for 3 h to further enhance their electrical activity.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

Analytical Electron Microscopy of Surface-Modified Ceramics

1985 ◽  
Vol 43 ◽  
pp. 276-279
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Theoretical Models ◽  
Ceramic Materials ◽  
Solute Concentration ◽  
Second Phase ◽  
Analytical Electron ◽  
Implantation Techniques ◽  
Lattice Damage ◽  
Surface Modified

Over the past several years, it has become increasingly evident that materials for proposed advanced energy systems will be required to operate at high temperatures and in aggressive environments. These constraints make structural ceramics attractive materials for these systems. However it is well known that the condition of the specimen surface of ceramic materials is often critical in controlling properties such as fracture toughness, oxidation resistance, and wear resistance. Ion implantation techniques offer the potential of overcoming some of the surface related limitations.While the effects of implantation on surface sensitive properties may be measured indpendently, it is important to understand the microstructural evolution leading to these changes. Analytical electron microscopy provides a useful tool for characterizing the microstructures produced in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer, and annealing behavior. Such analyses allow correlations to be made with theoretical models, property measurements, and results of complimentary techniques.

High-resolution electron microscopy of nanostructured materials

1995 ◽  
Vol 53 ◽  
pp. 172-173
Author(s):  
M. José-Yacamán
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Nanostructured Materials ◽  
High Resolution Electron Microscopy ◽  
Hrem Image ◽  
Small Particles ◽  
Resolution Electron ◽  
Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

scholarly journals Analysis of Stresses and Strains around Dislocations at Grain Boundaries by Quantitative High-Resolution Electron Microscopy

2006 ◽  
Vol 12 (S02) ◽  
pp. 894-895
Author(s):  
M Hytch ◽  
J-L Putaux ◽  
J Thibault
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

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

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