Modeling of Dislocations in an Epitaxial Island Structure

2001 ◽  
Vol 673 ◽  
Author(s):  
X. H. Liu ◽  
F. M. Ross ◽  
K. W. Schwarz
Keyword(s):  
Dislocation Loop ◽  
Lattice Mismatch ◽  
Growth Behavior ◽  
Dislocation Dynamics ◽  
Stress Fields ◽  
Island Structure ◽  
Modeling Techniques ◽  
Multi Level ◽  
Good Agreement

ABSTRACTWe present calculations of dislocations in CoSi2 islands grown by reactive epitaxy on a Si(111) substrate. The stress fields due to the lattice mismatch are calculated with standard FEM techniques, and are converted into a structured, multi-level and multi-grid stress table that is imported into the PARANOID code to study the dislocation dynamics. Single and multiple dislocations in the island have been simulated, and the predicted patterns are strikingly similar to those observed experimentally. By looking at the growth behavior of very small loops we also find that dislocation-loop nucleation becomes easier as the islands become larger, and that thick islands are dislocated at smaller sizes than thin ones. These results are also in good agreement with experimental observations. We conclude that current modeling techniques are sufficient to treat this type of problem at a useful level of accuracy.

Disorientations in dislocation structures: Formation and spatial correlation

2002 ◽  
Vol 17 (9) ◽  
pp. 2433-2441 ◽  
Author(s):  
Wolfgang Pantleon
Keyword(s):  
Plastic Deformation ◽  
Spatial Correlation ◽  
Distribution Functions ◽  
Scaling Behavior ◽  
Dislocation Dynamics ◽  
Slip Systems ◽  
Experimental Findings ◽  
Good Agreement

During plastic deformation, dislocation boundaries are formed and orientation differences across them arise. Two different causes lead to the formation of two kinds of deformation-induced boundaries: a statistical trapping of dislocations in incidental dislocation boundaries and a difference in the activation of slip systems on both sides of geometrically necessary boundaries. On the basis of these mechanisms, the occurrence of disorientations across both types of dislocation boundaries is modeled by dislocation dynamics. The resulting evolution of the disorientation angles with strain is in good agreement with experimental observations. The theoretically obtained distribution functions for the disorientation angles describe the experimental findings well and explain their scaling behavior. The model also predicts correlations between disorientations in neighboring boundaries, and evidence for their existence is presented.

ION BEAM (Cu–Pb–Sn) IMPLANTATION OF SURFACE LAYER OF 30ChGSN2A

2018 ◽  
Vol 25 (07) ◽  
pp. 1950011
Author(s):  
YU. M. BOROVIN ◽  
E. V. LUKYANENKO ◽  
V. V. OVCHINNIKOV ◽  
T. YU. SKAKOVA ◽  
N. V. UCHEVATKINA ◽  
...  
Keyword(s):  
Surface Layer ◽  
Elastic Stress ◽  
Ion Beam ◽  
Stress Fields ◽  
Internal Stresses ◽  
Lead Alloy ◽  
Mechanism Of Formation ◽  
Rotational Deformation ◽  
Multi Level ◽  
Copper Lead

Electron microscopy studies were conducted for the fine structure of ion-doped layer on 30ChGSN2A steel obtained by ion implantation of monotectic tin-doped copper–lead alloy Cu64Pb36[Formula: see text]Sn. Formation of a multi-level hierarchical structure was detected. The features of formation of each layer were analyzed, and it was found that the main mechanism of formation of these structures is diffusion and relaxation resulting in the occurrence of internal stresses both in the surface layer and in the sheet of 30ChGSN2A steel. Relaxation of elastic stress fields results in translational–rotational deformation forming various vortex structures.

scholarly journals Depth-Resolved Microspectroscopy of Porous Silicon Multilayers

1999 ◽  
Vol 588 ◽  
Author(s):  
S. Manotas ◽  
F. Agulló-Rueda ◽  
J. D. Moreno ◽  
R. J. Martín-Palma ◽  
R. Guerrero-Lemus ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Silicon Nanocrystals ◽  
Phonon Frequency ◽  
Lattice Mismatch ◽  
High Porosity ◽  
Phonon Confinement ◽  
Heating Effects ◽  
Average Size ◽  
Good Agreement

AbstractWe have measured micro-photoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. We find noticeable differences in the spectra of layers with different porosity, as expected from the quantum confinement of electrons and phonons in silicon nanocrystals with different average sizes. The PL emission band gets stronger, blue shifts, and narrows at the high porosity layers. The average size can be estimated from the shift. The Raman phonon band at 520 cm−1 weakens and broadens asymmetrically towards the low energy side. The line shape can be related quantitatively with the average size by the phonon confinement model. To get a good agreement with the model we add a band at around 480 cm−1, which has been attributed to amorphous silicon. We also have to leave as free parameters the bulk silicon phonon frequency and its line width, which depend on temperature and stress. We reduced laser power to eliminate heating effects. Then we use the change of frequency with depth to monitor the stress. At the interface with the substrate we find a compressive stress in excess of 10 kbar, which agrees with the reported lattice mismatch. Finally, average sizes are larger than those estimated from PL.

Multi-level fracture network model for coupled seepage and stress fields in rock mass

2003 ◽  
Vol 20 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Chai Junrui ◽  
Li Shouyi ◽  
Wu Yanqing
Keyword(s):  
Rock Mass ◽  
Network Model ◽  
Fracture Network ◽  
Stress Fields ◽  
Multi Level

Grain Growth Behavior of Al2O3-ZrO2 with a Small Amount of Zirconia

2007 ◽  
Vol 561-565 ◽  
pp. 535-538 ◽  
Author(s):  
M. Nagashima ◽  
Motozo Hayakawa
Keyword(s):  
Growth Inhibition ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Sintering Temperature ◽  
Growth Behavior ◽  
Pinning Effect ◽  
Grain Growth Behavior ◽  
Good Agreement ◽  
Zirconia Content

Grain growth behavior in Al2O3 with a small amount of ZrO2 (< 5 vol%) was examined. Grain growth of Al2O3 was retarded by zirconia particles, despite the small amount of added zirconia. The fraction of the zirconia particles embedded within alumina grains (intragranular zirconia particles) increased with decreasing zirconia content and increasing sintering temperature. Grain growth inhibition of alumina in the Al2O3-ZrO2 showed good agreement with the prediction of modified Zener’s pinning effect by the zirconia particles on grain boundaries.

scholarly journals Nucleation and dynamics of dislocations in mismatched heterostructures

2001 ◽  
Vol 696 ◽  
Author(s):  
Marco Patriarca ◽  
Antti Kuronen ◽  
Kimmo Kaski
Keyword(s):  
Graphical User Interface ◽  
Lattice Mismatch ◽  
Dislocation Nucleation ◽  
Dislocation Dynamics ◽  
Dynamics Model ◽  
Simulation Code ◽  
System Temperature ◽  
Basic Parameters ◽  
On Line ◽  
Energy Mapping

AbstractIn this paper we have investigated, through computer simulations, dislocation nucleation and dislocation dynamics in a heterostructure system with the lattice-mismatch interface, i.e. a system with internal strain. In particular, we have studied the dependence of the nucleation thresholds on the basic parameters of the crystals, such as the amount of mismatch and the system temperature. These studies have been carried out by using the simulation code with a graphical user interface developed at our laboratory. This on-line simulation system produces a real time interactive visualization of the 3-D Molecular Dynamics model. Furthermore, it detects the presence of dislocations and tracks them by an algorithm based on potential energy mapping.

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