scholarly journals Impurity diffusion activation energies in Al from first principles

2009 ◽  
Vol 79 (5) ◽  
Author(s):  
Darko Simonovic ◽  
Marcel H. F. Sluiter
Keyword(s):  
First Principles ◽  
Activation Energies ◽  
Impurity Diffusion ◽  
Diffusion Activation

Hg1-xCdxTe: Defect Structure Overview

1990 ◽  
Vol 216 ◽  
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.

Tracer Impurity Diffusion in Liquid Metals: K in Na and Na in K

1973 ◽  
Vol 28 (1) ◽  
pp. 117-119
Author(s):  
T. Persson ◽  
S. J. Larsson
Keyword(s):  
Liquid Metals ◽  
Activation Energies ◽  
Impurity Diffusion ◽  
Effective Activation ◽  
Kcal Mole ◽  
Self Diffusion

The diffusivities of 42K in Na and of 24Na in K have been measured between 100 ° and 285 °C, utilizing an „infinite capillary" technique. The results are adequately described by the Arrhenius relations (in cm2/s) DK in Na = 0.46 · 10-3 exp (-1.82/RT) and DNa in K = 0.93 · 10-3 exp (-2.11/RT). The differences ΔQ in effective activation energies between impurity diffusion and self-diffusion are about -0.4 kcal/mole for Na and +0.1 kcal/mole for K. This can be satisfactorily explained by electrostatic screening arguments. The impurity diffuses slower than the host atoms in Na, faster in K.

Growth Mechanism of Si Dimer Rows on Si(001)

1995 ◽  
Vol 408 ◽  
Author(s):  
T. Yamasaki ◽  
T. Uda ◽  
K. Terakura
Keyword(s):  
Molecular Dynamics ◽  
High Temperatures ◽  
Growth Mechanism ◽  
First Principles ◽  
Activation Energies ◽  
Molecular Dynamics Method ◽  
Perpendicular Direction ◽  
Condensation Process ◽  
Growth Processes ◽  
Dynamics Method

AbstractInitial processes of Si dimer row growth on Si(001) surface is studied by the first principles molecular dynamics method. We optimize several different ad-Si clusters composed of one to four atoms on the surface and estimate activation energies for some important growth processes. At lower temperatures, a metastable ad-Si dimer in the trough between substrate dimer rows attracts monomers and tends to grow into a short diluted-dimer row in the perpendicular direction to the substrate dimer rows. In high temperatures as ad-Si dimers can diffuse, a direct dimer condensation process is possible to elongate the dense-dimer rows also in the perpendicular direction.

scholarly journals First-principles study of vacancy-assisted impurity diffusion in ZnO

APL Materials ◽  
2014 ◽  
Vol 2 (9) ◽  
pp. 096101 ◽  
Author(s):  
Daniel Steiauf ◽  
John L. Lyons ◽  
Anderson Janotti ◽  
Chris G. Van de Walle
Keyword(s):  
First Principles ◽  
Impurity Diffusion ◽  
First Principles Study

Positron trapping and self-diffusion activation energies in chromium

1979 ◽  
Vol 19 (2) ◽  
pp. 149-152 ◽  
Author(s):  
J. L. Campbell ◽  
C. W. Schulte
Keyword(s):  
Activation Energies ◽  
Self Diffusion ◽  
Positron Trapping ◽  
Diffusion Activation

Fundamental Interactions of Fe in Silicon: First-Principles Theory

2007 ◽  
Vol 131-133 ◽  
pp. 233-240 ◽  
Author(s):  
Stefan K. Estreicher ◽  
Mahdi Sanati ◽  
N. Gonzalez Szwacki
Keyword(s):  
First Principles ◽  
Activation Energies ◽  
Spin States ◽  
Hydrogen Passivation ◽  
First Principles Calculations ◽  
Native Defects ◽  
Fundamental Interactions ◽  
Recombination Centers

Interstitial iron and iron-acceptor pairs are well studied but undesirable defects in Si as they are strong recombination centers which resist hydrogen passivation. Thermal anneals often result in the precipitation of Fe. Relatively little information is available about the interactions between Fe and native defects or common impurities in Si. We present the results of first-principles calculations of Fe interactions with native defects (vacancy, self-interstitial) and common impurities such as C, O, H, or Fe. The goal is to understand the fundamental chemistry of Fe in Si, identify and characterize the type of complexes that occur. We predict the configurations, charge and spin states, binding and activation energies, and estimate the position of gap levels. The possibility of passivation is discussed.

A computer simulation study of point defects in diopside and the self-diffusion of Mg and Ca by a vacancy mechanism

1998 ◽  
Vol 62 (5) ◽  
pp. 599-606 ◽  
Author(s):  
Feridoon Azough ◽  
Robert Freer ◽  
Kate Wright ◽  
Robert Jackson
Keyword(s):  
Computer Simulation ◽  
Elevated Temperatures ◽  
Defect Formation ◽  
Diffusion Path ◽  
Activation Energies ◽  
Vacancy Mechanism ◽  
Self Diffusion ◽  
Direct Route ◽  
Formation Energies ◽  
Diffusion Activation

AbstractComputer simulation techniques have been used to investigate defect formation and the diffusion of Ca and Mg in diopside. It was found that isolated, non-interacting CaO and MgO Schottky defects had the lowest formation energies (3.66 and 3.97 eV respectively); oxygen Frenkel defects are the most favourable oxygen defects (formation energies 3.93 eV). Magnesium and calcium self-diffusion in the c-direction of diopside is easiest by a vacancy mechanism involving either direct jumps along the c-direction, or double jumps in the b-c plane. In the extrinsic regime, diffusion activation energies for Mg are predicted to be 9.82 eV (direct route) and 1.97 eV (double jump route); for Ca diffusion, activation energies are predicted to be 6.62 eV (direct route) and 5.63 eV (double jump route). If additional vacancies (oxygen or magnesium) are present in the vicinity of the diffusion path, Ca migration energies fall to 1.97–2.59 eV. At elevated temperatures in the intrinsic regime, diffusion activation energies of ⩾ 5.95 eV are predicted for Mg self-diffusion and 9.29–10.28 eV for Ca self-diffusion. The values for Ca diffusion are comparable with published experimental data. It is inferred that a divacancy mechanism may operate in diopside crystals.

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