Ab-Initio Pseudopotential Calculations of Phosphorus Diffusion in Silicon

AbstractIn traditional models of P diffusion in Si, vacancy assisted diffusion mechanism has been assumed. More recently, experiments have determined that for intrinsic P diffusion in Si, the interstitial assisted diffusion mechanism dominates. We have performed ab-initio pseudopotential calculations to study P diffusion in Si. Special care is taken with regard to structure minimization, charge state effects and corrections. We calculated the defect formation energies and migration barriers for the various competing P-interstitial complex diffusion mechanisms for low concentration P region, as well as the energetics of different charge states P-vacancy complex diffusion. For interstitial mediated diffusion of P-Sii pair in Si, we find the overall diffusion activation energies calculated are 3.1 eV for neutral case, and 3.4 eV for +1 charge case. This is in agreement with experimental observation that the interstitial mechanism dominates for intrinsic P diffusion in Si. For vacancy mediated diffusion, our calculations are in agreement with previous calculations result in the neutral case. We obtained the lower bounds for diffusion activation energy of 3.8 eV for (PV)0 and 3.4 eV for (PV). A further evaluation of the numbers would require a proper treatment of the energy states in the band-gap due to Jahn-Teller relaxations.

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Diffusion Mechanism and Kinetics of Diffusion Bonded Mg/Ni/Al Joint

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.616.286 ◽

2014 ◽

Vol 616 ◽

pp. 286-290

Author(s):

Jian Zhang ◽

Qiang Guo Luo ◽

Qiang Shen ◽

Lian Meng Zhang

Keyword(s):

Heating Temperature ◽

Diffusion Mechanism ◽

Diffusion Activation Energy ◽

X Ray Diffraction ◽

X Ray ◽

Atom Diffusion ◽

Mechanism And Kinetics ◽

Ni Interlayer ◽

Kinetics Of ◽

Diffusion Activation

Mg and Al were bonded successfully by means of diffusion bonding using Ni interlayer. The microstructure, diffusion mechanism and regulation of atom diffusion were investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis analysis (EPMA). The results showed that the joints consisted of Mg-Ni interface and Al-Ni interface, and there were Mg2Ni formed in the Mg-Ni interface and Al3Ni formed in the Al-Ni interface, respectively. Diffusion activation energy of Mg and Al were lower than that of Ni in the Mg-Ni and Al-Ni interface. The thickness (x) of Mg2Ni and Al3Ni can be expressed as x2=3.97×10-4 exp (-139600/RT) (t-t0) and x2=8.62×10-3 exp (-174200/RT) (t-t0) with heating temperature (T) and holding time (t).

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Atomic Diffusion of Al and Si in Cu44.25Ag14.75Zr36Ti5 Bulk Metallic Glass

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.510.804 ◽

2012 ◽

Vol 510 ◽

pp. 804-807

Author(s):

Wei Yuan Yu ◽

You Liang Wang ◽

Wen Jiang Lu

Keyword(s):

Diffusion Coefficient ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Diffusion Mechanism ◽

Base Material ◽

Atomic Diffusion ◽

Diffusion Activation Energy ◽

Metal Atoms ◽

Secondary Ion ◽

Diffusion Activation

Secondary ion mass spectroscopy (SIMS) has been adopted to study the diffusion of Al and Si in Cu44.25Ag14.75Zr36Ti5bulk metallic glass (BMG). It has been found that around the transition temperature of metallic glass, the relation between its diffusion coefficient and the temperature satisfy the same Arrhenius relation, which means the metallic transition has not caused change to the diffusion mechanism. In addition, the radius of Al atom is close to that of Si atom, but under the same temperature and time condition, the diffusion coefficient of Si atom in bulk metallic glass (BMG) is twice that of the Al atom, while there is not a big difference in diffusion activation energy. This is because as non-metallic element, the radius of Si atom has a strong binding force with the metal atoms in the base material, which also has a bigger diffusion coefficient.

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Diffusion of ion implanted indium and silver in ZnO crystals

MRS Proceedings ◽

10.1557/opl.2012.696 ◽

2012 ◽

Vol 1394 ◽

Cited By ~ 2

Author(s):

Faisal Yaqoob ◽

Mengbing Huang

Keyword(s):

Activation Energy ◽

Total Dose ◽

Gas Flow ◽

Defect Formation ◽

Activation Energies ◽

Substitutional Impurity ◽

Impurity Atoms ◽

And Migration ◽

Diffusion Activation ◽

Ion Implanted

ABSTRACTWe report on diffusion behavior for ion implanted indium and silver atoms in ZnO crystals. Both In and Ag ions were implanted at room temperature at 7-10° relative to c-axis to avoid channeling effects during implantation. In ions were implanted at four different energies (40, 100, 200, and 350 keV, respectively) and doses (4.20×1013, 6.70×1013, 8.10×1013 and 3.10×1014 /cm2, respectively), resulting in a total dose of 5 ×1014 /cm2. For another set of ZnO samples, Ag ions were implanted at energies 30, 75, 150, and 350 keV at doses 3.3×1013, 4.2×1013, 8.3×1013 and 3.4×1014 /cm2, respectively, to reach a total dose of 5×1014 /cm2. Both In and Ag implants resulted in a uniform concentration profile of the implanted dopants from surface to depth ~ 150 nm. The samples were annealed for 30 minutes at temperatures between 850-1050 °C in an oxygen gas flow. The distributions of In and Ag atoms, either aligned or nonaligned along the crystalline directions, were measured by Rutherford backscattering combined with ion channeling. The diffusivities for nonaligned (interstitial) and aligned (substitutional) dopants atoms were determined to vary with annealing temperature via the Arrhenius relationship. The diffusion activation energies (Ea) along the <10-11> direction for substitutional impurity atoms were lower than those for interstitial dopants atoms e.g., in the case of In, Ea ~ 1.52 eV for <10-11> aligned In atoms and Ea ~ 2.61 eV for interstitial In atoms between <10-11> atomic rows and in the case of Ag, Ea ~ 1.77 eV for the interstitial Ag atoms between the <10-11> atomic rows and 1.11 eV for <10-11> aligned Ag atoms. The diffusion activation energies showed a different trend for the two dopants as measured along the <0001> crystalline direction. For Ag implanted in ZnO, the activation energy of Ea ~ 0.91 eV for the aligned Ag atoms along <0001> direction and Ea ~ 1.55 eV were found for the interstitial Ag atoms, whereas in the case of In along the <0001> direction, the interstitial In was found to migrate with a higher activation energy (Ea ~ 1.78 eV) than the substitutional In (Ea ~1.42 eV). These results will be compared with first-principle calculations for understanding the energetics of defect formation and migration in both n- and p-type doping cases.

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The formation and migration of non-equivalent oxygen vacancies in PrBaCo2−xMxO6−δ, where M = Fe, Co, Ni and Cu

Physical Chemistry Chemical Physics ◽

10.1039/d0cp05497f ◽

2021 ◽

Vol 23 (3) ◽

pp. 2313-2319

Author(s):

V. P. Zhukov ◽

E. V. Chulkov ◽

B. V. Politov ◽

A. Yu. Suntsov ◽

V. L. Kozhevnikov

Keyword(s):

High Temperature ◽

Ab Initio ◽

Thermodynamic Functions ◽

Oxygen Vacancies ◽

Defect Formation ◽

And Migration ◽

Formation Energies

The ab initio calculated defect formation energies are used for assessment of high-temperature thermodynamic functions that govern the appearance of oxygen vacancies in PrBaCo2−xMxO6−δ.

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Calculation of Diffusion Coefficients in γ-Ni

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.795.15 ◽

2019 ◽

Vol 795 ◽

pp. 15-21

Author(s):

Yuan Liu ◽

Qin Sheng Wang ◽

Rachel C. Thomson ◽

Steven Kenny

Keyword(s):

Diffusion Coefficients ◽

Energy Barrier ◽

Density Functional ◽

Formation Energy ◽

Diffusion Mechanism ◽

Diffusion Activation Energy ◽

Reasonable Accuracy ◽

Functional Theory ◽

Diffusion Activation ◽

Limited Diffusion

A model has been developed to predict the interdiffusion behaviour of elements between a substrate and a coating. This model, however, relies on knowing accurate diffusion coefficients. However, only limited diffusion data are available in the literature. Recently, it has been demonstrated that Density Functional Theory (DFT) can be used to calculate relevant diffusion coefficients with reasonable accuracy. According to the vacancy diffusion mechanism , diffusion coefficient has an Arrhenius form. The diffusion activation energy can be written as a sum of the diffusion energy barrier and the vacancy formation energy adjacent to a solute.

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Diffusion of oxygen in hypostoichiometric uranium dioxide nanocrystals. A molecular dynamics simulation

Chimica Techno Acta ◽

10.15826/chimtech.2021.8.1.07 ◽

2021 ◽

Vol 8 (1) ◽

pp. 20218107

Author(s):

K. A. Nekrasov ◽

A. E. Galashev ◽

D. D. Seitov ◽

S. K. Gupta

Keyword(s):

Oxygen Diffusion ◽

Diffusion Mechanism ◽

Quantitative Agreement ◽

Dynamics Simulation ◽

Diffusion Activation Energy ◽

Oxygen Anions ◽

D Values ◽

Range Of Values ◽

Diffusion Activation ◽

Weakly Dependent

A molecular dynamic simulation of diffusion of intrinsic oxygen anions in the bulk of hypostoichiometric UO2-x nanocrystals with a free surface was carried out. The main diffusion mechanism turned out to be the migration of oxygen by the anionic vacancies. It is shown that in the range of values of the non-stoichiometry parameter 0.05 £x £ 0.275 the oxygen diffusion coefficient D is weakly dependent on temperature, despite the uniform distribution of the vacancies over the model crystallite. The reliable D values calculated for the temperature T = 923 K are in the range from 3×10-9 to 7×10-8 cm2/s, in quantitative agreement with the experimental data. The corresponding diffusion activation energy is in the range from 0.57 eV to 0.65 eV, depending on the interaction potentials used for the calculations.

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Ab initio band theory approach to electron energy loss near edge structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104595 ◽

1988 ◽

Vol 46 ◽

pp. 506-507

Author(s):

Xudong Weng ◽

O.F. Sankey ◽

Peter Rez

Keyword(s):

Ab Initio ◽

Local Density ◽

Interpolation Method ◽

Atomic Orbital ◽

Plane Waves ◽

Large Set ◽

Theory Approach ◽

Band Theory ◽

Atomic Orbitals ◽

Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

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Ab initio calculation of formation and migration volumes for vacancies in Li and Na

Physical Review B ◽

10.1103/physrevb.55.5772 ◽

1997 ◽

Vol 55 (9) ◽

pp. 5772-5777 ◽

Cited By ~ 22

Author(s):

U. Breier ◽

V. Schott ◽

M. Fähnle

Keyword(s):

Ab Initio ◽

Ab Initio Calculation ◽

And Migration

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Hg1-xCdxTe: Defect Structure Overview

MRS Proceedings ◽

10.1557/proc-216-3 ◽

1990 ◽

Vol 216 ◽

Cited By ~ 7

Author(s):

M.A. Berding ◽

A. Sher ◽

A.-B. Chen

Keyword(s):

Point Defects ◽

Defect Structure ◽

Defect Formation ◽

Activation Energies ◽

Mass Action ◽

Native Defect ◽

Native Point Defects ◽

Vacancy Migration ◽

Formation Energies ◽

Diffusion Activation

ABSTRACTNative point defects play an important role in HgCdTe. Here we discuss some of the relevant mass action equations, and use recently calculated defect formation energies to discuss relative defect concentrations. In agreement with experiment, the Hg vacancy is found to be the dominant native defect to accommodate excess tellurium. Preliminary estimates find the Hg antisite and the Hg interstitial to be of comparable densities. Our calculated defect formation energies are also consistent with measured diffusion activation energies, assuming the interstitial and vacancy migration energies are small.

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