Atomic structure of misfit dislocations in nonpolar ZnO/Al2O3 heterostructures

2010 ◽  
Vol 97 (12) ◽  
pp. 121914 ◽  
Author(s):  
H. Zhou ◽  
M. F. Chisholm ◽  
P. Pant ◽  
H. J. Chang ◽  
J. Gazquez ◽  
...  
Keyword(s):  
Atomic Structure ◽  
Misfit Dislocations

Atomic structure of stair rod misfit dislocations at the GaAs on Si(100) interface

1990 ◽  
Vol 48 (4) ◽  
pp. 342-343
Author(s):  
D. Gerthsen
Keyword(s):  
Lattice Constant ◽  
Atomic Structure ◽  
Spherical Aberration ◽  
Stacking Faults ◽  
Misfit Dislocations ◽  
Gaas On Si ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Intersection Line ◽  
Oriented Parallel

The prospect of technical applications has induced a lot of interest in the atomic structure of the GaAs on Si(100) interface and the defects in its vicinity which are often studied by high resolution transmission electron microscopy. The interface structure is determined by the 4.1% lattice constant mismatch between GaAs and Si, the large difference between the thermal expansion coefficients and the polar/nonpolar nature of the GaAs on Si interface. The lattice constant mismatch is compensated by misfit dislocations which are characterized by a/2<110> Burgers vectors b which are oriented parallel or inclined on {111} planes with respect to the interface. Stacking faults are also frequently observed. They are terminated by partial dislocations with b = a/6<112> on {111} planes. In this report, the atomic structure of stair rod misfit dislocations is analysed which are located at the intersection line of two stacking faults at the interface.A very thin, discontinous film of GaAs has been grown by MBE on a Si(100) substrate. Fig.1.a. shows an interface section of a 27 nm wide GaAs island along [110] containing a stair rod dislocation. The image has been taken with a JEOL 2000EX with a spherical aberration constant Cs = 1 mm, a spread of focus Δz = 10 nm and an angle of beam convergence ϑ of 2 mrad.

Quasiperiodic interfaces: HREM observations of grain and phase boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 332-333
Author(s):  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
Direct Determination ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Atomic Structures ◽  
Periodic Arrays ◽  
Parameter Ratio ◽  
Metal Metal

The atomic structures of internal interfaces have recently received considerable attention, not only because of their importance in determining many materials properties, but also because the atomic structure of many interfaces has become accessible to direct atomic-scale observation by modem HREM instruments. In this communication, several interface structures are examined by HREM in terms of their structural periodicities along the interface.It is well known that heterophase boundaries are generally formed by two low-index planes. Often, as is the case in many fcc metal/metal and metal/metal-oxide systems, low energy boundaries form in the cube-on-cube orientation on (111). Since the lattice parameter ratio between the two materials generally is not a rational number, such boundaries are incommensurate. Therefore, even though periodic arrays of misfit dislocations have been observed by TEM techniques for numerous heterophase systems, such interfaces are quasiperiodic on an atomic scale. Interfaces with misfit dislocations are semicoherent, where atomically well-matched regions alternate with regions of misfit. When the misfit is large, misfit localization is often difficult to detect, and direct determination of the atomic structure of the interface from HREM alone, may not be possible.

Atomic structure of misfit dislocations at InAs/GaAs(110)

2008 ◽  
Vol 20 (23) ◽  
pp. 235227 ◽  
Author(s):  
R Choudhury ◽  
D R Bowler ◽  
M J Gillan
Keyword(s):  
Atomic Structure ◽  
Misfit Dislocations

Atomic structure of epitaxial Nb-Al2O3 interfaces II. Misfit dislocations

1997 ◽  
Vol 75 (5) ◽  
pp. 1357-1382 ◽  
Author(s):  
G. Gutekunst ◽  
J. Mayer ◽  
V. Vitek ◽  
M. Rühle
Keyword(s):  
Atomic Structure ◽  
Misfit Dislocations

On the atomic structure of the Nb/Al2O3 interface and the growth of Al2O3 particles

1989 ◽  
Vol 4 (4) ◽  
pp. 972-977 ◽  
Author(s):  
M. Kuwabara ◽  
J. C. H. Spence ◽  
M. Ruhle
Keyword(s):  
Internal Oxidation ◽  
Growth Mechanism ◽  
Atomic Structure ◽  
Standoff Distance ◽  
Recent Theory ◽  
Misfit Dislocations ◽  
Final Layer ◽  
Metal Ceramic ◽  
Atomically Flat ◽  
Good Agreement

The growth mechanism for small precipitates of Al2O3 formed by internal oxidation in the Nb–Al2O3 interface is studied in detail. The observations show that the Nb (001)/Al2O3 (00.1) interface is almost atomically flat and that there are no interface compounds. We suggest that the final layer on the Al2O3 side of this interface consists of oxygen atoms. The effects of image forces on misfit dislocations are found to result in a standoff distance between dislocation cores and the interface, in good agreement with the recent theory. The implications of this for the strength of metal-ceramic bonding are discussed.

Atomic structure of misfit dislocations in metal‐ceramic interfaces

1995 ◽  
Vol 71 (6) ◽  
pp. 1219-1239 ◽  
Author(s):  
V. Vitek ◽  
G. Gutekunst ◽  
J. Mayer ◽  
M. Rühle
Keyword(s):  
Atomic Structure ◽  
Misfit Dislocations ◽  
Metal Ceramic ◽  
Ceramic Interfaces

Atomic Structure of Ag/Ni Interfaces

1990 ◽  
Vol 183 ◽  
Author(s):  
Y. Gao ◽  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Special Technique ◽  
Misfit Dislocations ◽  
Lattice Statics ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Small Lattice ◽  
Model Structures

AbstractWhile in heterophase systems of small lattice parameter differences, misfit dislocations are often formed at the interface, it is not known, whether and in which form, misfit localization occurs when the misfit is very large. The atomic structure of Ag/Ni interfaces (misfit 14%) was studied by high-resolution electron microscopy (HREM). A special technique was developed to prepare interface specimens suitable for HREM observations.Lattice statics calculations, using embedded-atom potentials, were performed to determine the structure and energies of Ag/Ni interfaces. The lowest interfacial energy was found for the cube-on-cube orientation and (111) interfaces. This is in agreement with the experimental observation, that all interfaces are strongly faceted with (111)Ag/(111)Ni facets.Misfit localization was found by HREM and computer simulation. The HREM observations will be compared to images derived from image simulations, based on model structures obtained from embedded atom calculations.

scholarly journals Comparisons Of Observed And Simulated Atomic Structures Of Pd/NiO Heterophase Interfaces

1992 ◽  
Vol 295 ◽  
Author(s):  
M. I. Buckett ◽  
J. P. Shaffer ◽  
Karl L. Merkle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Rigid Body ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Boundary Plane ◽  
Misfit Dislocations ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Image Simulations

AbstractHigh-resolution electron microscopy (HREM) and image simulations using the multislice algorithm have been used to study the atomic structure of a Pd/NiO (111) interface in an intemally oxidized sample. Samples prepared in this way result in cube-on-cube oriented or twin-related precipitates whose (111) interfaces exhibit a contrast modulation along the boundary plane in HREM images. Previous studies have reported that the observed structural period of this modulation corresponds qualitatively to the expected spacing if the boundary was composed of a network of misfit dislocations. In this study, rigid models of the (111) interface as viewed from the [110] direction were simulated using the EMS suite of programs. The questions we address are: (1) whether the terminating plane on the oxide side is made up of a Ni or an 0 layer, and (2) whether a rigid body translation normal to the interface exists. Finally, the results of the simulations are compared and contrasted to through-focal experimental images to investigate the origin of the contrast modulations and their possible relation to the extent of the misfit localization in these systems.

Radiation-induced surface decomposition

1983 ◽  
Vol 41 ◽  
pp. 368-369
Author(s):  
M. L. Knotek
Keyword(s):  
Ionizing Radiation ◽  
Atomic Structure ◽  
Chemical Bonding ◽  
Neutral Species ◽  
Radiation Induced ◽  
Physical And Chemical ◽  
Surface Decomposition ◽  
The Relationship ◽  
Electron And Photon ◽  
Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

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