Crystalline Particles in Thermally Grown Silicon Dioxide

1982 ◽  
Vol 14 ◽  
Author(s):  
F. A. Ponce ◽  
T. Yamashita
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Silicon Dioxide ◽  
Silicon Layer ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Lattice Images ◽  
Thermally Grown

ABSTRACTSmall crystalline particles in the vicinity of the Si/SiO2 interface have been directly observed by high resolution transmission electron microscopy. These crystallites have typical diameters between 20 and 120 Å. Based on the observed interplanar spacings and angles in lattice images, the structure of these particles has been found to match those of cristobalite. Some orientation relationships also appear to exist between these particles and the silicon layer.

Structural study of Cd(S,Se) doped glasses. High-resolution transmission electron microscopy (HRTEM) assisted by image processing

1990 ◽  
Vol 23 (5) ◽  
pp. 418-423 ◽  
Author(s):  
M. Allais ◽  
M. Gandais
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Bulk Material ◽  
Optical Filters ◽  
Characteristic Size ◽  
Transmission Electron ◽  
Doped Glasses ◽  
Lattice Images ◽  
Average Size

High-resolution transmission electron microscopy (HRTEM) was used for examining Cd(S,Se) nanocrystals grown in silicate glasses commercially available as optical filters. The lattice images of the nanocrystals were numerated and submitted to filtering through Fourier transformation in order to sweep off the background signal originating mainly from glass. Optical filters from several firms were examined. The nanocrystals have been identified with Cd(S,Se) compounds crystallized in the wurzite structure, as in bulk material. The lattice images indicate crystallites having the shape of hexagonal prisms a little elongated along the c axis. The distribution of grain size differs according to the filter: the smallest size being about 1.5 nm (threshold for detection), the largest size varies from 7 to 10 nm, the average size sa , from 3–4 to 5–6 nm and the characteristic size sc from 5–6 to 7–8 nm (sc is the size of grains occupying the main part of the crystallized volume).

Preparation of vermiculites for HRTEM

Clay Minerals ◽  
1989 ◽  
Vol 24 (1) ◽  
pp. 23-32 ◽  
Author(s):  
CH. Marcks ◽  
H. Wachsmuth ◽  
H. Graf V. Reichenbach
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Computer Simulation ◽  
High Resolution ◽  
Alkyl Chains ◽  
Transmission Electron ◽  
Lattice Images ◽  
Silicate Layers

AbstractA technique for preparing vermiculites for examination by high-resolution transmission electron microscopy (HRTEM) has been developed. A TEM-stable expanded phase can be obtained by intercalating n-alkylammonium ions between the silicate layers of a parent biotite. The vermiculite particles were embedded in Spurr resin and centrifuged to improve orientation. Ultra-thin specimens were prepared using an ultramicrotome, the quality and thickness of the sections being monitored by TEM. Lattice images of biotite, Ba-vermiculite and octylammonium-vermiculite, the latter showing a perpendicular arrangement of the alkyl chains relative to the silicate layers, were obtained with a resolution ∼2 Å. The reliability of these images was confirmed by computer simulation.

High-resolution transmission electron microscopy: A structural and chemical probe of semiconductor systems

1987 ◽  
Vol 45 ◽  
pp. 332-333
Author(s):  
A. Ourmazd
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Structural Information ◽  
Image Interpretation ◽  
Lattice Image ◽  
Semiconductor Interfaces ◽  
Transmission Electron ◽  
Lattice Images ◽  
The Individual

High Resolution Transmission Electron Microscopy (HRTEM) is now a powerful probe for the structural analysis of semiconductor systems. Lattice images can be obtained in a number of orientations, in at least three of which the individual atomic columns can be resolved. However, there exits an important class of problems, whose resolution requires chemical as well as structural information. The identification of individual atomic columns in compound semiconductors, and the atomic configuration of semiconductor/semiconductor interfaces are two important examples.In general, most reflection used to form a lattice image are not particularly sensitive to chemical changes in the sample. The information content of a typical lattice image is therefore strongly dominated by structural details. On the other hand, reflections such as the (200), which are normally forbidden in the diamond structure, come about in the zinc-blende system because of the chemical differences between the occupants of the two sublattices, and are thus highly chemically sensitive. In the “kinematical” thickness region, where simple image interpretation is possible, such reflections are relatively weak and their contribution to the lattice image is dominated by the stronger and chemically insensitive, allowed reflections.

Quantitative determination of imaging parameters and composition from high-resolution transmission electron microscopy lattice images

1996 ◽  
Vol 54 ◽  
pp. 96-97
Author(s):  
D. Stenkamp
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Sample Thickness ◽  
Inelastic Electron ◽  
Local Composition ◽  
Transmission Electron ◽  
Non Linear ◽  
Lattice Images

A quantitative method for the direct determination of defocus Δf, local sample thickness t and local composition x from high-resolution transmission electron microscopy (HRTEM) lattice images of wedge-shaped samples is described. The method is applicable to a wide class of crystalline materials comprising elemental semiconductors, elemental metals and substitutional random alloys composed of these elements. The proposed method relies on the functional dependence of linear and non-linear image Fourier coefficients on the parameters defocus Δf, sample thickness t and composition x. This relationship is analytically derived by application of the Bloch wave formalism and the non-linear imaging theory to the HRTEM imaging process. Influences of inelastic electron scattering and partially coherent illumination conditions are taken into account explicitly.

High Resolution Transmission Electron Microscopy of GaAs/AlAs Hetero-Structures in the Projection

1990 ◽  
Vol 183 ◽  
Author(s):  
N. Ikarashi ◽  
A. Sakai ◽  
T. Baba ◽  
K. Ishida ◽  
J. Motohisa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Focus Condition ◽  
Lattice Images ◽  
The Difference ◽  
Imaging Conditions

AbstractHigh resolution transmission electron microscopy (HRTEM) of GaAs/AlAs hetero-structures grown by molecular beam epitaxy (MBE) is carried out in the <110> projection. It is shown that GaAs and AlAs are distinguished clearly by the difference in their lattice images at the samples thicknesses of about 15–30 nm under near Scherzer focus condition. Under these imaging conditions, very thin films consist of single monolayer AlAs are observed. Vicinal interfaces of GaAs/AlAs which were grown on (001) substrate misoriented toward [110] are also examined in the [110] projection. The interfacial structures are imaged edgeon, so that the fluctuations of terrace width, and the roughness of step-edges at these interfaces are observed on an atomic scale.

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