Atomic Structure of Si(111)-(5×2)-Au from High Resolution Electron Microscopy and Heavy-Atom Holography

1995 ◽  
Vol 75 (11) ◽  
pp. 2172-2175 ◽  
Author(s):  
L. D. Marks ◽  
R. Plass
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.


1998 ◽  
Vol 4 (S2) ◽  
pp. 762-763
Author(s):  
V. Vitek

Since interfaces and grain boundaries affect critically many properties of materials, their atomic structure has been investigated very extensively using computer modeling. Most of these calculations have been made using semi-empirical central-force descriptions of atomic interactions, recently primarily the embedded-atom type many-body potentials. Owing to the approximate nature of such schemes, a connection with experimental observations that can validate the calculations is essential. The high resolution electron microscopy (HREM) is such experimental technique and it has, indeed, been frequently combined with calculations of interfacial structure and chemistry. In fact such a link is not only important for verification of the results of computer modeling but also crucial for meaningful interpretation of HREM observations. Hence, coupling the atomistic modeling with HREM is a synergistic procedure. It not only leads to better understanding of interfacial structures but may contribute significantly to the validation and assessment of limits of the schemes used for the description of atomic interactions.


Author(s):  
M. K. Lamvik ◽  
J. M. Pullman ◽  
A. V. Crewe

Negative staining and high resolution shadowing have been extensively used for structural studies in electron microscopy. However, these techniques cover the specimen with a layer of heavy salt or metal, and hence do not allow determination of true mass distribution or localization of specific sites using heavy atom markers. A prerequisite for such structural studies is an examination of unstained specimens. For thin specimens dark field microscopy must be used to obtain adequate contrast. The scanning transmission electron microscope is preferred for such studies since elastic, energyloss, and unscattered electrons can be recorded and analyzed quantitatively to form images with a minimum of beam-induced damage.


1999 ◽  
Vol 589 ◽  
Author(s):  
V. Potin ◽  
G. Nouet ◽  
P. Ruterana ◽  
R.C. Pond

AbstractThe studied GaN layers are made of mosaYc grains rotated around the c-axis by angles in the range 0-25°. Using high-resolution electron microscopy, anisotropic elasticity calculations and image simulation, we have analyzed the atomic structure of the edge threading dislocations. Here, we present an analysis of the Σ = 7 boundary using circuit mapping in order to define the Burgers vectors of the primary and secondary dislocations. The atomic structure of the primary ones was found to exhibit 5/7 and 8 atom cycles.


2000 ◽  
Vol 6 (S2) ◽  
pp. 1044-1045
Author(s):  
C.J.D. Hetherington ◽  
U. Dahmen

Grain boundaries in fee metals with low stacking fault energy are known to undergo extended relaxations that can at times lead to a thin layer of a different structure. In Cu, for example, it has been found that ∑3﹛ 112﹜ boundaries relax into a 9R phase [1]. In this work, we have used high resolution electron microscopy to investigate the atomic structure of ∑3 grain boundaries in mazed bicrystal films of Au. Using ﹛111﹜ Ge surfaces as a template, Au bicrystals can be grown in two orientation variants, related to each other by a 60° rotation about the surface normal. As described previously, such films have a strong tendency to facet onto the coherent twin plane parallel to the substrate [2], also known as “double positioning” [3]. If films are made very thin, the likelihood for such in-plane boundaries to lie in the foil decreases, and it becomes possible to observe the atomic structure of edge-on interfaces along <111>.


1997 ◽  
Vol 482 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
H. Amano ◽  
I. Akasaki ◽  
...  

AbstractHigh resolution electron microscopy (HREM) was applied to study atomic structure of stacking faults, grain boundaries and interfaces in III-nitrides epitaxial layers grown by MOVPE on sapphire. Defects formed in GaN epitaxial layers grown by MOVPE were reviewed in comparison with those in MBE grown materials


1993 ◽  
Vol 8 (1) ◽  
pp. 24-37 ◽  
Author(s):  
William Krakow ◽  
David P. DiVincenzo ◽  
Peter A. Bancel ◽  
Eric Cockayne ◽  
Veit Elser

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