Interfacial and twin boundary structures of nanostructured Cu–Ag filamentary composites

2003 ◽  
Vol 18 (9) ◽  
pp. 2194-2202 ◽  
Author(s):  
K. H. Lee ◽  
S. I. Hong
Keyword(s):  
Twin Boundary ◽  
Lattice Misfit ◽  
Longitudinal Section ◽  
Copper Matrix ◽  
Misfit Strain ◽  
Boundary Structure ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
The Matrix ◽  
Twinning Shear

A high-resolution transmission electron microscope was used to study the interfacial and twin boundary structure of nanostructured Cu–Ag filamentary composites. Copper matrix and silver filaments have the orientation relationship {111}Cu∥{111}Ag and 〈111〉Cu∥〈111〉Ag. In some regions, twin bands propagated through the silver filaments with some boundary steps at the matrix/filament interface, and the silver filament appeared to be kinked in the twin band in the same direction as the twinning shear. This suggests that twins propagated after the formation of silver filament, and twin bands were deformation twins. At the matrix/filament interface, misfit interface dislocations were introduced periodically to relieve the misfit strain. The distance between interfacial misfit dislocations along the matrix/filament interface in the longitudinal section was measured to be 1.88 nm, which is in good agreement with that (1.81 nm) calculated based on lattice misfit. In Cu–Ag nanocomposites, the spacing between Moire fringes was found to be quite close to that between interfacial misfit dislocations.

Mechanisms of misfit strain relaxation in epitaxially grown BLT (Bi4-xLaxTi3O12, x = 0.75) thin films

2003 ◽  
Vol 779 ◽  
Author(s):  
Hyung Seok Kim ◽  
Sang Ho Oh ◽  
Ju Hyung Suh ◽  
Chan Gyung Park
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
20 Nm

AbstractMechanisms of misfit strain relaxation in epitaxially grown Bi4-xLaxTi3O12 (BLT) thin films deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, that was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (~1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film.

Coherency Strain of an Overgrown Island

1989 ◽  
Vol 148 ◽  
Author(s):  
J. K. Lee ◽  
S. A. Hackney
Keyword(s):  
Single Phase ◽  
Lattice Misfit ◽  
Alloy System ◽  
Misfit Strain ◽  
Chemical Thermodynamics ◽  
Misfit Dislocations ◽  
Two Phase ◽  
Single Phase State ◽  
Ε Phase ◽  
Binary Alloy System

ABSTRACTThe lattice misfit strain in an overgrown island is considered to be accommodated by twodistinctive domains; a pure coherency domain (ε domain) and a domain of misfit dislocations (δ domain). By introducing such two different constituents, the model predicts the transition condition from a “single phase” state (ε phase) to a “two-phase mixture” (ε+δ) as a function of misfit strain. Further, as in the chemical thermodynamics of a binary alloy system, energy vs. misfit strain diagrams allow us to understand possible existence of various metastable states which may be associated with an overgrowth.

Direct Observations of Relaxation of Si/SiGe/Si on Insulator

2010 ◽  
Vol 1262 ◽  
Author(s):  
Tongda Ma ◽  
Hailing Tu
Keyword(s):  
Misfit Dislocation ◽  
Room Temperature ◽  
Sige Layer ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Direct Observations ◽  
Transmission Electron ◽  
Dislocation Behavior ◽  
Film Specimen

AbstractMicrostructural evolution is directly observed when the cross-sectional film specimen of Si/SiGe/Si on insulator (Si/SiGe/SOI) is heated from room temperature (R.T., 291 K) up to 1113 K in high voltage transmission electron microscope (HVEM). The misfit dislocation at the lower interface of the SiGe layer begins to extend downwards even at 913 K. The lower interface takes the lead in roughening against the upper interface of the SiGe layer. The roughened interface is ascribed to elastic relaxation. As misfit strain is partially transferred to SOI top Si layer and misfit dislocation is prolonged at the lower interface, the roughened interface turns smooth again. Thereafter, the misfit dislocations are introduced into the upper roughened interface of the SiGe layer to release the increased misfit strain. It is suggested that the microscopic relaxation of the SiGe layer is related to dislocation behavior and strain transfer.

The Initial Stages of MBE Growth of InSb on GaAs(100) - A High Misfit Heterointerface

1989 ◽  
Vol 159 ◽  
Author(s):  
C.J. Kiely ◽  
A. Rockett ◽  
J-I. Chyi ◽  
H. Morkoc
Keyword(s):  
Three Dimensional ◽  
Misfit Strain ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Mbe Growth ◽  
Edge Type ◽  
Transmission Electron ◽  
Interfacial Defects ◽  
Square Array

ABSTRACTThe initial stages of heteroepitaxy of InSb on GaAs(100) grown by MBE have been studied by transmission electron microscopy. Three dimensional InSb island growth occurs in which the majority of the 14.6% misfit strain is accommodated by a square array of a/2<011= edge-type misfit dislocations. The implications of each island having a well defined defect array before coalescence into a continuous epilayer are discussed. Some 600-type a/2<101= interfacial defects and associated threading dislocations are also observed in coalesced films and possible reasons for their existence are explained. A strong asymmetrical distribution of planar defects in the InSb islands is observed and the origin of the asymmetry is discussed. Finally some evidence for local intermixing in the vicinity of the interface is presented.

TEM Studies of Grain Boundary Structure in a Cast Polycrystalline Silicon

2005 ◽  
Vol 475-479 ◽  
pp. 1673-1676 ◽  
Author(s):  
Isamu Kuchiwaki ◽  
Takahiro Hirabayashi ◽  
Hiroshi Fukushima
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Twin Boundary ◽  
Polycrystalline Silicon ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Resolution Electron ◽  
The Difference

Cast polycrystalline silicon for solar cell contains mostly straight twin boundaries which are thought to have little effect on the electrical activity. There are, however, some complicated grain boundaries in it. One of these boundaries consists of slightly curved and straight parts. The structure of this boundary was analyzed to investigate the difference of these two types of boundaries. The conventional transmission electron microscopy (TEM) found that this slightly curved boundary was the zigzag shaped boundary made by (11 _ ,2) and ( _ ,211) planes. High resolution electron microscopy (HREM) confirmed that (11 _ ,2) plane was the boundary of {112} Σ3 twin boundary which formed a straight grain boundary at the other end of the analyzed grain boundary, and also confirmed that ( _ ,2 11) plane was also the boundary of {112} Σ3 twin boundary which intersected with the former twin boundary at an angle of 120 [deg].

A Comparison of the Structural Quality of High-In Content InGaAsN Films Grown on InGaAs Pseudosubstrate and on GaAs Substrate

2007 ◽  
Vol 31 ◽  
pp. 221-223
Author(s):  
S. Sanorpim ◽  
P. Kongjaeng ◽  
R. Katayama ◽  
Kentaro Onabe
Keyword(s):  
Electron Microscopy ◽  
Gaas Substrate ◽  
Misfit Strain ◽  
The Other ◽  
Buffer Layers ◽  
Structural Quality ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Lattice Matched

The use of an InGaAs buffer layer was applied to the growth of thick InxGa1-xAs1-yNy layers with higher In contents (x > 30%). In order to obtain the lattice-matched InGaAsN layer having the bandgap of 1.0 eV, the In0.2Ga0.8As was chosen. In this work, the In0.3Ga0.7As0.98N0.02 layers were successfully grown on closely lattice-matched In0.2Ga0.8As buffer layers (InGaAsN/InGaAs). Structural quality of such layers is discussed in comparison with those of the In0.3Ga0.7As0.98N0.02 layers grown directly on the GaAs substrate (InGaAsN/GaAs). Based on the results of transmission electron microscopy, the misfit dislocations (MDs), which are located near the InGaAsN/GaAs heteroepitaxial interface, are visible by their strain contrast. On the other hand, no generation of the MDs is evidenced in the InGaAsN layer grown on the In0.2Ga0.8As pseudosubstrate. Our results demonstrate that a reduction of misfit strain though the use of the pseudosubstrate made possible the growth of high In-content InGaAsN layers with higher crystal quality to extend the wavelength of InGaAsN material.

Strain Relaxation in GaAs on Si by Two Groups of Misfit Dislocations

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Tamura ◽  
T. Saitoh ◽  
T. Yodo
Keyword(s):  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Plan View ◽  
Partial Dislocations ◽  
Group I ◽  
Transmission Electron ◽  
Before And After ◽  
Gaas Films

ABSTRACTHigh-resolution cross-sectional and conventional plan-view transmission electron microscope observations have been carried out for molecular beam epitaxially grown GaAs films on vicinal Si (001) as a function of film thicknesses and observation directions between two orthogonal <110> directions before and after annealing. Two groups of misfit dislocations are characterized by analyzing whether their extra half planes exist in the film and the substrate side. The group I misfit dislocations due to a stress caused by a lattice misfit between GaAs and Si consist of partial and, 60° and 90° complete dislocations in an as-grown state. After annealing partial dislocations almost disappear and 90° perfect dislocations are predominantly observed. The group II misfit dislocations due to a thermal-expansion misfit-induced stress are all of the 60° type complete dislocations, independent of film thickness and annealing.

scholarly journals Reorientation of Misfit Dislocations During Annealing in InGaAs/GaAs(001) Interfaces

1993 ◽  
Vol 308 ◽  
Author(s):  
Y. Chen ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
J.F. Klem ◽  
J.Y. Tsao
Keyword(s):  
Strain Relaxation ◽  
Dislocation Line ◽  
Line Tension ◽  
Misfit Strain ◽  
Relaxation Mechanism ◽  
Misfit Dislocations ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Edge Component ◽  
Interfacial Plane

ABSTRACTTransmission electron microscopy is applied to investigate the effect of post-annealing on misfit dislocations in an In0.2Ga0.8As/GaAs(001) heterostructure. An orthogonal array of 60º dislocations along [110] and [110] directions was observed in the interfaces of the samples grown by MBE at 520 ºC. When the as-grown samples were annealed at temperatures ranging from 600 to 800 ºC, the 60º dislocations were gradually reoriented by dislocation reactions occurring at the 90º intersections followed by nonconservative motion driven by dislocation line tension and the residual elastic misfit strain. The final result of this process was a dislocation array lying along [100] and [010] directions. The reoriented u=<100> dislocation has a Burgers vector , which is the same as that of 60º dislocation, but the edge component of its Burgers vector in the (001) interfacial plane is larger than that of 60º dislocation by a factor of , resulting in a greater contribution to elastic strain relaxation. This nonconservative reorientation of 60º dislocations to form the u=<100> dislocations represents a new strain relaxation mechanism in diamond or zinc blende semiconductor heterostructures.

Single domain structure of 2H-AlN films on Si(001) substrates

2001 ◽  
Vol 680 ◽  
Author(s):  
Joerg Jinschek ◽  
Vadim Lebedev ◽  
Ute Kaiser ◽  
Wolfgang Richter
Keyword(s):  
Surface Defects ◽  
Substrate Surface ◽  
Lattice Misfit ◽  
Film Structure ◽  
Single Domain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Aln Film ◽  
Lattice Planes

ABSTRACTAluminum nitride (2H-AlN) films were grown by plasma-assisted molecular beam epitaxy (MBE) on Si(001). By conventional (CTEM) and high resolution transmission electron microscopy (HRTEM) investigations the influence of the off-axis angle of the substrate surface on the film structure was studied. Three types of Si(001) substrates were used: on-axis, ∼1°, and ∼5° off-axis. The 2H-AlN layer on an exact oriented Si(001) substrates consists of 3 AlN film domains: two main film domains, AlNI and AlNII, and a small domain AlNIII at substrate surface defects. Their c-axis orientations are parallel to the c-axis of the substrate: [0001]AlNI,II,III ∥ [001]Si. The a-axes of AlNI and AlNII rotated by 30° to each other: [11 20]AlNII∥[01 10]AlNII ∥ [1 1 0]Si. The orientation of AlNIII is [01 10]AlNIII ∥ [100]Si. In 2H-AlN films grown on off-axis Si(001) substrates (∼1° and ∼5°) the ratio between the AlNI and AlNII film domains changes dramatically as far as a single domain film structure consisting of mainly AlNI is reached. The AlN c-axes of all domains on the off-axis substrates are not parallel to the Si c-axis but tilted by the off-axis angle of the Si(001) substrate (∼1° respectively ∼5°), i.e. [0001]AlN is parallel to the Si(001) substrate surface orientation. Determination of the AlNI domain / Si(001) interface structure by HRTEM illuminates the origin of the preference of this domain in the 2H-AlN film by using off-axis Si(001) substrates. On the on-axis substrate a regular array of misfit dislocations causes a 5:4 fit between the (1 1 00)AlN and ( 1 1 0)Si lattice planes. The off-axis Si(001) leads to a rotation of the AlN lattice in respect of the Si lattice. An array of misfit dislocations with a 4:3 fit between (1 1 01)AlN and ( 1 1 1)Si lattice planes decreases the residual lattice misfit from -1.6% to -0.8%.

Formation of Interfacial Dislocations in Hetero-Epitaxial Layers Grown in Two-Dimensional Mode

1995 ◽  
Vol 399 ◽  
Author(s):  
S. Oktyabrsky ◽  
J. Narayan
Keyword(s):  
Compressive Strain ◽  
Elastic Interaction ◽  
Misfit Strain ◽  
Layer Growth ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Layer By Layer ◽  
Two Dimensional ◽  
Transmission Electron ◽  
Interfacial Dislocations

ABSTRACTHigh-resolution transmission electron microscopy has been used to study formation of interfacial defects related to misfit strain accommodation in Ge/Si heterostructures (mismatch 4%) grown in the two-dimensional mode. Special emphasis is placed on the conditions leading to a two-dimensional (layer-by-layer) growth mode. We discuss general features of a dislocation tangle resulted from glide-limited plastic relaxation, typical for highly mismatched (001)-diamond and zinc-blende heterostructures. The evolution of the dislocation network as a function of film thickness and thermal annealing is controlled by growth instabilities and dislocation interactions. The observed correlation in distribution of parallel misfit dislocations including pairing (at <2 nm) of misfit segments from intersecting glide planes and rearrangements in a nonequilibrium dislocation network driven by elastic interaction between 60° dislocation segments in the almost relaxed heterostructures are discussed in detail. Pairing of the 60° glide dislocations results either in their combination to form pure edge 90° dislocations or in the dissociation into partials. We propose and experimentally verify a model for the latter process involving the formation of extrinsic stacking faults in the heterolayers under compressive strain.

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