Atomic-Scale Measurement of Structure and Chemistry of a Single-Unit-Cell Layer of LaAlO3 Embedded in SrTiO3

2013 ◽  
Vol 19 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Chun-Lin Jia ◽  
Juri Barthel ◽  
Felix Gunkel ◽  
Regina Dittmann ◽  
Susanne Hoffmann-Eifert ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Materials Science ◽  
Single Layer ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Atomic Scale ◽  
Chemical Information ◽  
Nominal Thickness ◽  
Specimen Area

AbstractA single layer of LaAlO3 with a nominal thickness of one unit cell, which is sandwiched between a SrTiO3 substrate and a SrTiO3 capping layer, is quantitatively investigated by high-resolution transmission electron microscopy. By the use of an aberration-corrected electron microscope and by employing sophisticated numerical image simulation procedures, significant progress is made in two aspects. First, the structural as well as the chemical features of the interface are determined simultaneously on an atomic scale from the same specimen area. Second, the evaluation of the structural and chemical data is carried out in a fully quantitative way on the basis of the absolute image contrast, which has not been achieved so far in materials science investigations using high-resolution electron microscopy. Considering the strong influence of even subtle structural details on the electronic properties of interfaces in oxide materials, a fully quantitative interface analysis, which makes positional data available with picometer precision together with the related chemical information, can contribute to a better understanding of the functionality of such interfaces.

X-Ray-Optical Multilayer Structures Studied Using High Resolution Electron Microscopy.

1986 ◽  
Vol 77 ◽  
Author(s):  
Mary Beth Stearns ◽  
Amanda K. Petford-Long ◽  
C.-H. Chang ◽  
D. G. Stearns ◽  
N. M. Ceglio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Degree Of Crystallinity ◽  
Multilayer Systems ◽  
Layer Width ◽  
X Ray ◽  
Resolution Electron

ABSTRACTThe technique of high resolution electron microscopy has been used to examine the structure of several multilayer systems (MLS) on an atomic scale. Mo/Si multilayers, in use in a number of x-ray optical element applications, and Mo/Si multilayers, of interest because of their magnetic properties, have been imaged in cross-section. Layer thicknesses, flatness and smoothness have been analysed: the layer width can vary by up to 0.6nm from the average value, and the layer flatness depends on the quality of the substrate surface for amorphous MLS, and on the details of the crystalline growth for the crystalline materials. The degree of crystallinity and the crystal orientation within the layers have also been investigated. In both cases, the high-Z layers are predominantly crystalline and the Si layers appear amorphous. Amorphous interfacial regions are visible between the Mo and Si layers, and crystalline cobalt suicide interfacial regions between the Co and Si layers. Using the structural measurements obtained from the HREM results, theoretical x-ray reflectivity behaviour has been calculated. It fits the experimental data very well.

High-Resolution-Electron-Microscopy Investigation of Nanosize Inclusions

MRS Bulletin ◽  
1997 ◽  
Vol 22 (8) ◽  
pp. 49-52 ◽  
Author(s):  
U. Dahmen ◽  
E. Johnson ◽  
S.Q. Xiao ◽  
A. Johansen
Keyword(s):  
Electron Microscopy ◽  
Melting Point ◽  
Giant Magnetoresistance ◽  
Materials Science ◽  
Semiconductor Nanocrystals ◽  
High Resolution Electron Microscopy ◽  
Solid Particles ◽  
Atomic Scale ◽  
Size And Shape ◽  
New Frontier

The behavior of solids in the nanometer size regime, as their dimensions approach the atomic scale, is of increasing fundamental and applied interest in materials research. Electronic, optical, magnetic, mechanical, or thermodynamic properties all may depend on the size and shape of the solid. As a result, in the nanoscale regime, size and shape may be used as design variables to tailor a material's properties such as giant magnetoresistance in multilayer films, or the optical properties in semiconductor nanocrystals. In most cases, the size dependence of properties is not well-understood. Nanophase materials constitute a new frontier in materials science, and accurate nanoscale characterization is extremely important in exploring this new frontier. In this area, transmission electron microscopy (TEM) plays a key role. Because of its unique ability to provide information on the structure and composition of internal interfaces in solids, TEM is particularly important in cases of buried nanophase structures such as small solid inclusions—that is, solid particles embedded within another solid.Nanoscale inclusions have recently been shown to exhibit unusual melting behavior that depends strongly on their size and the embedding matrix. For example, small inclusions of Pb in SiO exhibit melting-point depressions of several hundred degrees, whereas similarsized Pb inclusions in aluminum have shown large increases in melting point. Although a full understanding of these effects is still lacking, it appears that they are related not just to inclusion size but also to their shape and interface structure.

Atomic Scale Study of Cosi/Si (111) and CoSi2/Si (111) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
A. Catana ◽  
M. Heintze ◽  
P.E. Schmid ◽  
P. Stadelmann
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Orientation Relationship ◽  
Cross Sections ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Initial Stage ◽  
Resolution Electron

ABSTRACTHigh Resolution Electron Microscopy (HREM) was used to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. CoSi is found to grow epitaxially on Si with [111]Si // [111]CoSi and < 110 >Si // < 112 >CoSi. Two CoSi non-equivalent orientations (rotated by 180° around the substrate normal) can occur in this plane. They can be clearly distinguished by HRTEM on cross-sections ( electron beam along [110]Si). At about 500°C CoSi transforms to CoSi2. Experimental results show that the type B orientation relationship satisfying [110]Si // [112]CoSi is preserved after the initial stage of CoSi2 formation. At this stage an epitaxial CoSi/CoSi2/Si(111) system is obtained. The atomic scale investigation of the CoSi2/Si interface shows that a 7-fold coordination of the cobalt atoms is observed in both type A and type B epitaxies.

Interfacial Atomic Structures During Cobalt Silicidation

1990 ◽  
Vol 202 ◽  
Author(s):  
A. Catana ◽  
P.E. Schmid
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Cross Sectional ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Predominant Orientation ◽  
Lower Temperature

ABSTRACTHigh Resolution Electron Microscopy (HREM) and image calculations are combined to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. The samples are prepared by UHV e-beam evaporation of Co layers (2 nm) followed by annealing at 300°C or 400°C. Cross-sectional observations at an atomic scale show that the silicidation of Co at the lower temperature yields epitaxial CoSi/Si domains such that [111]Si // [111]CoSi and <110>Si // <112>CoSi. At about 400°C CoSi2 nucleates at the CoSi/Si interface. During the early stages of this chemical reaction, an epitaxial CoSi/CoSi2/Si system is observed. The predominant orientation is such that (021) CoSi planes are parallel to (220) CoSi2 planes, the CoSi2/Si interface being of type B. The growth of CoSi2 is shown to proceed at the expense of both CoSi and Si.

Defect fluorite structures containing Bi 2 O 3 : the system Bi 2 O 3 -Nb 2 O 5

1986 ◽  
Vol 406 (1831) ◽  
pp. 173-182 ◽  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Electron Diffraction ◽  
Pyrochlore Structure ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Compositional Range ◽  
Resolution Electron ◽  
Structural Principles

A previously described solid solution in the system Bi 2 O 3 -Nb 2 O 5 based on the δ-Bi 2 O 3 structure has been reinvestigated by electron diffraction and high resolution electron microscopy. Four distinct phases have been found, all of which are based upon defect fluorite structures, and the structural principles of the phase with the greatest compositional range have been elucidated. This involves an adaption of elements of the pyrochlore structure with an ordering of niobium-oxygen octahedra into groups lying on the {111} planes of an enlarged cubic unit cell, separated by a matrix of δ-Bi 2 O 3 structure.

The Observation Of Mg)-Al Interface By Hrem and Microdiffraction

1985 ◽  
Vol 43 ◽  
pp. 240-241
Author(s):  
S.Y. Zhang ◽  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Materials Science ◽  
Incident Beam ◽  
High Resolution Electron Microscopy ◽  
Interface Structure ◽  
Resolution Electron ◽  
Powerful Means ◽  
Interface Structures

The combination of high resolution electron microscopy (HREM) and nanodiffraction techniques provided a powerful means for characterizing many of the interface structures which are of fundamental importance in materials science. In this work the interface structure between magnesium oxide and aluminum has been examined by HREM (with JEM-200CX) and nanodiffraction (with HB-5). The interfaces were formed by evaporating Al on freshly prepared cubic MgO smoke crystals under various vacuum conditions, at 10 -4, 10-5 10-6 and 10-7 torr. The Al layers on the MgO (001) surface are about 100Å thick. TEM observations were performed with the incident beam along the MgO [100] direction so that the interface could be revealed clearly. The nanodiffraction patterns were obtained with the electron beam of 15Å diameter parallel to the interface.

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