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D C Chrzan - One of the best experts on this subject based on the ideXlab platform.
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structure and energy of the Partial Dislocation cores in gaas
Physica Status Solidi B-basic Solid State Physics, 2006Co-Authors: S P Beckman, D C ChrzanAbstract:A methodology for investigating isolated a and β Partial Dislocations in III-V semiconductors is presented. Using this method the 30° and 90°, a and β Partial Dislocations in GaAs are investigated. The structures of the proposed core reconstructions are investigated. For the 90° Partials, two reconstructions have been proposed. The relative energies of the two reconstructions are investigated in addition to the structural investigation.
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structures of glide set 90 Partial Dislocation cores in diamond cubic semiconductors
Physica B-condensed Matter, 2003Co-Authors: D C Chrzan, S P BeckmanAbstract:Two core reconstructions of the 90° Partial Dislocations in diamond cubic semiconductors, the so-called single- and double-period structures, are often found to be nearly degenerate in energy. This near degeneracy suggests the possibility that both core reconstructions may be present simultaneously along the same Dislocation core, with the domain sizes of the competing reconstructions dependent on temperature and the local stress state. To explore this dependence, a simple statistical mechanics-based model of the Dislocation core reconstructions is developed and analyzed. Predictions for the temperature-dependent structure of the Dislocation core are presented.
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boundary conditions for Dislocation core structure studies application to the 90 Partial Dislocation in silicon
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2001Co-Authors: Karin Lin, D C ChrzanAbstract:The effects of boundary conditions on studies of Dislocation cores are examined, using the 90° Partial Dislocation in Si as an illustration. The relative stability of two possible reconstructions of the core are explored using periodic supercell calculations and cylindrical boundary conditions and the results compared. It is argued that the stable core structure depends systematically on the stress field experienced by the Dislocation, and that this dependence can be quantified effectively using a combination of periodic supercells and elasticity theory.
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structure and energy of the 90 degrees Partial Dislocation in diamond a combined ab initio and elasticity theory analysis
Physical Review Letters, 2000Co-Authors: X Blase, Karin Lin, A Canning, Steven G Louie, D C ChrzanAbstract:The core structure and stability of the 90 degrees Partial Dislocation in diamond is studied within isotropic elasticity theory and ab initio total energy calculations. The double-period reconstruction is found to be more stable than the single-period reconstruction for a broad range of stress states. The analysis of the ab initio results shows further that elasticity theory is valid for Dislocation spacings as small as 10-20 A, thus allowing ab initio calculations to provide reliable parameters for continuum theory analysis.
Chaoying Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of 30 Partial Dislocation and stacking fault on na and mg storage and diffusion in si anode
Computational Materials Science, 2016Co-Authors: Chaoying Wang, Tianyi Sang, Lijun Yang, Zhenqing WangAbstract:Abstract While the perfect Si can’t be used to store Na and Mg interstitials in Na-ion batteries (NIBs) and Mg-ion batteries (MIBs), the defects of 30° Partial Dislocation and stacking fault (SF) may improve the performance of Si anode according to the multi-scale simulation results. It is found that both 30° Partial Dislocation and SF can provide more stable sites to accommodate impurities and enhance the binding strengths. The 30° Partial Dislocation can drastically promote the binding energies of Na (Mg) to the value of 0.72 (0.622) eV and 0.684 (0.6) eV at Oct-A and Oct-B, respectively. Moreover, it is thermodynamically and kinetically favorable for Na and Mg concentrating in the defect areas. On the other side, the migration barriers of Na and Mg in the 30° Partial Dislocation and SF are much higher than the defect-free Si. Those defects may restrict the diffusion of interstitials and turn into limiting factors of charge/discharge rate of NIBs and MIBs.
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multi scale simulation of the stability and diffusion of lithium in the presence of a 90 Partial Dislocation in silicon
Journal of Applied Physics, 2014Co-Authors: Chaoying Wang, Qingyuan Meng, Lijun Yang, Wei Zhao, Baolai WangAbstract:The stable positions, binding energies, and dynamic properties of Li impurity in the presence of a 90° Partial Dislocation in Si have been studied by using the multi-scale simulation method. The corresponding results are compared with the defect-free Si crystal in order to reflect how the Dislocation defect affects the performances of Li-ion batteries (LIBs) at the atomic level. It is found that the inserted Li atom in the Dislocation core and nearest regions is more stable, since the binding energies are 0.13 eV to 0.52 eV larger than the bulk Si. Moreover, it is easier for Li atom to diffuse into those defect areas and harder to diffuse out. Thus, Li dopant may tend to congregate in the Dislocation core and nearest regions. On the other side, the 90° Partial Dislocation can glide in the {111} plane accompanied by the diffusion of Li impurity along the pentagon ring of core. In addition, the spacious heptagon ring of Dislocation core can lower the migration barrier of Li atom from 0.63 eV to 0.34 eV, which will enhance the motion of the dopant. Therefore, the presence of 90° Partial Dislocations may provide a fast and favorable diffusion path for the congregated Li impurity, which finally facilitates the lithiation of LIBs.
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multi scale simulation of lithium diffusion in the presence of a 30 Partial Dislocation and stacking fault in si
Journal of Applied Physics, 2014Co-Authors: Chaoying Wang, Qingyuan Meng, Lijun Yang, Wei Zhao, Baolai WangAbstract:The multi-scale simulation method is employed to investigate how defects affect the performances of Li-ion batteries (LIBs). The stable positions, binding energies and dynamics properties of Li impurity in Si with a 30° Partial Dislocation and stacking fault (SF) have been studied in comparison with the ideal crystal. It is found that the most table position is the tetrahedral (Td) site and the diffusion barrier is 0.63 eV in bulk Si. In the 30° Partial Dislocation core and SF region, the most stable positions are at the centers of the octagons (Oct-A and Oct-B) and pentahedron (site S), respectively. In addition, Li dopant may tend to congregate in these defects. The motion of Li along the Dislocation core are carried out by the transport among the Oct-A (Oct-B) sites with the barrier of 1.93 eV (1.12 eV). In the SF region, the diffusion barrier of Li is 0.91 eV. These two types of defects may retard the fast migration of Li dopant that is finally trapped by them. Thus, the presence of the 30° Partial di...
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interaction between the 30 Partial Dislocation and hex vacancy in silicon
Modern Physics Letters B, 2012Co-Authors: Chaoying Wang, Zhenqing Wang, Qingyuan MengAbstract:The molecular dynamics (MD) method is used to investigate the interaction between the 30° Partial Dislocation and hex-vacancy (V6) in Si. The interaction processes are described in detail and compared with the prior results of mono-vacancy (V1) and di-vacancy (V2). It is found that Dislocations are pinned by V6 when the shear stresses are smaller than a definite critical value τc. It illustrates that the encountered two segments beside vacant sites parallel each other or annihilate. Moreover, it is shown that the critical shear stress τc is mainly determined by both the migration barrier of kink and the volume of vacancy. Although V6 cannot make Dislocations move faster due to the present small models, it may lower the Dislocation density in certain conditions due to the pinning effect.
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dynamic properties of reconstruction defect on 90 Partial Dislocation in si
Physica Status Solidi B-basic Solid State Physics, 2012Co-Authors: Chaoying Wang, Qingyuan Meng, Zhenqing Wang, Zhaoying WangAbstract:The molecular dynamics (MD) and nudged elastic band (NEB) methods are employed to investigate the dynamic properties of the reconstruction defect (RD) on 90° Partial Dislocation in Si. This involves the motion of RD in single-period (SP-RD) and double-period (DP-RD) structures. When the temperature is lower than 1100 K, the migration processes and velocities of SP-RD can be simply observed. It is found that SP-RD is remarkably mobile, which is essentially determined by its structural characteristics. At relatively higher temperature, the previous prediction that SP-RD may act as the nucleating center of a double kink is proved. All these MD results are in good agreement with the calculated barriers. The migration of DP-RD is carried out by the motion of left–right kink RD complex (LR-RD) and right–left kink RD complex (RL-RD). Their motion sequences are described in detail and it is also found that the dangling bonds make the movement of the two complexes easier.
Wang Yongliang - One of the best experts on this subject based on the ideXlab platform.
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influence of the 90 Partial Dislocation core structure in silicon on energy levels
Solid State Communications, 1994Co-Authors: Sune Marklund, Wang YongliangAbstract:An LCAO-scheme taking into account 10 atomic orbitals (s-, p-, and d-type) is used to calculate the electronic structure of the reconstructed 90-degrees Partial Dislocation in Si. Two different valence force fields producing deviating results are used for modelling the core structure. Geometrical data published by another group is also used. The aim is to explore the influence of geometry on energy levels. We find that the band structure depends sensitively on bond angles. Using data determined by the Tersoff potential we obtain two bands of which the upper one penetrates deeply into the indirect band gap while the geometry minimizing the simple Keating potential leaves the gap completely clear of Dislocation states. Thus, from a theoretical point of view, the chief difficulty in calculating the electronic structure of the reconstructed 90-degrees Partial is the lack of accurate structural information.
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energy level calculations of the reconstructed 90 Partial Dislocation in silicon
Solid State Communications, 1992Co-Authors: Sune Marklund, Wang YongliangAbstract:Abstract An LCAO scheme taking into account 10 atomic orbitals ( s-, p- , and d -type) applied to a supercell containing 256 atoms is used to calculate the bound states of the reconstructed 90° Partial Dislocation in Si. The results differ significantly from our earlier calculations on the unreconstructed 90° Partial using the same method. We find two bands separate from each other in the entire Brillouin zone and the upper band penetrates deep into the indirect band gap which is in contradiction with the general opinion that core reconstruction clears the band gap of Dislocation states.
Karin Lin - One of the best experts on this subject based on the ideXlab platform.
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boundary conditions for Dislocation core structure studies application to the 90 Partial Dislocation in silicon
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2001Co-Authors: Karin Lin, D C ChrzanAbstract:The effects of boundary conditions on studies of Dislocation cores are examined, using the 90° Partial Dislocation in Si as an illustration. The relative stability of two possible reconstructions of the core are explored using periodic supercell calculations and cylindrical boundary conditions and the results compared. It is argued that the stable core structure depends systematically on the stress field experienced by the Dislocation, and that this dependence can be quantified effectively using a combination of periodic supercells and elasticity theory.
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structure and energy of the 90 degrees Partial Dislocation in diamond a combined ab initio and elasticity theory analysis
Physical Review Letters, 2000Co-Authors: X Blase, Karin Lin, A Canning, Steven G Louie, D C ChrzanAbstract:The core structure and stability of the 90 degrees Partial Dislocation in diamond is studied within isotropic elasticity theory and ab initio total energy calculations. The double-period reconstruction is found to be more stable than the single-period reconstruction for a broad range of stress states. The analysis of the ab initio results shows further that elasticity theory is valid for Dislocation spacings as small as 10-20 A, thus allowing ab initio calculations to provide reliable parameters for continuum theory analysis.
David Vanderbilt - One of the best experts on this subject based on the ideXlab platform.
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Models of core reconstruction for the 90 • Partial Dislocation in semiconductors Typeset using REVT E X 1
2020Co-Authors: R W Nunes, David VanderbiltAbstract:Abstract We compare the models that have been proposed in the literature for the atomic structure of the 90 • Partial Dislocation in the homopolar semiconductors, silicon, diamond, and germanium. In particular, we examine the traditional single-period and our recently proposed double-period core structures. Ab initio and tight-binding results on the core energies are discussed, and the geometries are compared in light of the available experimental information about Dislocations in these systems. The double-period geometry is found to be the ground-state structure in all three materials. We address boundaryconditions issues that have been recently raised about these results. The structures of point excitations (kinks, solitons, and kink-soliton complexes) in the two geometries are also reviewed
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models of core reconstruction for the 90 Partial Dislocation in semiconductors
Journal of Physics: Condensed Matter, 2000Co-Authors: R W Nunes, David VanderbiltAbstract:We compare the models that have been proposed in the literature for the atomic structure of the 90° Partial Dislocation in the homopolar semiconductors, silicon, diamond, and germanium. In particular, we examine the traditional single-period and our recently proposed double-period core structures. Ab initio and tight-binding results on the core energies are discussed, and the geometries are compared in the light of the available experimental information about Dislocations in these systems. The double-period geometry is found to be the ground-state structure for all three materials. We address boundary-condition issues that have been recently raised concerning these results. The structures of point excitations (kinks, solitons, and kink-soliton complexes) in the two geometries are also reviewed.
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models of core reconstruction for the 90 degree Partial Dislocation in semiconductors
arXiv: Materials Science, 2000Co-Authors: R W Nunes, David VanderbiltAbstract:We compare the models that have been proposed in the literature for the atomic structure of the 90-degree Partial Dislocation in the homopolar semiconductors, silicon, diamond, and germanium. In particular, we examine the traditional single-period and our recently proposed double-period core structures. Ab-initio and tight-binding results on the core energies are discussed, and the geometries are compared in light of the available experimental information about Dislocations in these systems. The double-period geometry is found to be the ground-state structure in all three materials. We address boundary-conditions issues that have been recently raised about these results. The structures of point excitations (kinks, solitons, and kink-soliton complexes) in the two geometries are also reviewed.
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core reconstruction of the 90 Partial Dislocation in nonpolar semiconductors
Physical Review B, 1998Co-Authors: J Bennetto, R W Nunes, David VanderbiltAbstract:We investigate the energetics of the single-period and double-period core reconstructions of the $90\ifmmode^\circ\else\textdegree\fi{}$ Partial Dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown to follow the same trends as the energy gap and the stiffness. Both structures are fully reconstructed, consisting entirely of fourfold coordinated atoms. They differ primarily in the detail of the local strains introduced by the two reconstructions in the core region. The double-period structure is shown to introduce smaller average bond-length deviations, at the expense of slightly larger average bond-angle bending distortions, with respect to the single-period core. The balance between these two strain components leads to the lower energy of the double-period reconstruction.
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core reconstruction of the 90 degree Partial Dislocation in non polar semiconductors
arXiv: Materials Science, 1998Co-Authors: R W Nunes, J Bennetto, David VanderbiltAbstract:We investigate the energetics of the single-period and double-period core reconstructions of the 90-degree Partial Dislocation in the homopolar semiconductors C, Si, and Ge. The double-period geometry is found to be lower in energy in all three materials, and the energy difference between the two geometries is shown to follow the same trends as the energy gap and the stiffness. Both structures are fully reconstructed, consisting entirely of fourfold coordinated atoms. They differ primarily in the detail of the local strains introduced by the the two reconstructions in the core region. The double-period structure is shown to introduce smaller average bond-length deviations, at the expense of slightly larger average bond-angle bending distortions, with respect to the single-period core. The balance between these two strain components leads to the lower energy of the double-period reconstruction.
