Atomistic Simulations of Point Defect Properties in Silicon

1992 ◽  
Vol 278 ◽  
Author(s):  
Dimitrios Maroudas ◽  
Robert A. Brown
Keyword(s):  
Distribution Function ◽  
Point Defects ◽  
Thermal Equilibrium ◽  
Harmonic Approximation ◽  
Reference State ◽  
Atomistic Simulations ◽  
Free Energies ◽  
Systematic Analysis ◽  
Equilibrium Concentrations ◽  
Cumulant Analysis

AbstractA systematic analysis based on atomistic simulations is presented for the calculation of energies and equilibrium concentrations of intrinsic point defects in silicon. Calculation of Gibbs free energies is based on the quasi-harmonic approximation for the reference state and the cumulant analysis of the enthalpy distribution function from Monte Carlo simulations in the reference state. Results are presented for the temperature dependence of enthalpies, volumes, and free energies of formation and thermal equilibrium concentrations of vacancies and self-interstitials.

The Influence of Point Defects on Diffusion and Gettering in Silicon

1984 ◽  
Vol 36 ◽  
Author(s):  
U. Gösele ◽  
T. Y. Tan
Keyword(s):  
Point Defects ◽  
Thermal Equilibrium ◽  
Nucleation And Growth ◽  
Impurity Diffusion ◽  
Intrinsic Point Defects ◽  
Different Types ◽  
Equilibrium Concentrations ◽  
Metallic Impurities

ABSTRACTIn a first part, we deal with the influence of intrinsic point defects (vacancies and self-interstitials) on self- and impurity diffusion in silicon. Estimates of the diffusivities and thermal equilibrium concentrations of vacancies and self-interstitials are given. In a second partwe discuss the influence of point defects on the diffusion and precipitation of different types of metallic impurities in various gettering schemes as well as on the nucleation and growth of SiO2 precipitates.

Intrinsic Point Defects and Diffusion Processes in Silicon

1983 ◽  
Vol 31 ◽  
Author(s):  
T. Y. Tan
Keyword(s):  
Point Defects ◽  
Thermal Equilibrium ◽  
Diffusion Processes ◽  
Equilibrium Concentration ◽  
Surface Oxidation ◽  
Self Diffusion ◽  
Equilibrium Concentrations ◽  
And Diffusion

ABSTRACTThis paper reviews recent progress in understanding the role of vacancies (V) and self-interstitials (I) in self and impurity diffusion in Si. Surface oxidation perturbs the thermal equilibrium concentration of point defects and analyses of the resulting effects on dopant diffusion showed that both V and I are present. Developments in experimental and theoretical works on Au diffusion in Si yielded a determination of the I-component and an estimate of the V-component of the Si self-diffusion coefficient. It is hoped that the I and V thermal equilibrium concentrations may be determined in the near future.A number of important physical aspects of the anomalous diffusion of P are now understood but a basically satisfactory model may need further work.

scholarly journals First Principles Calculations of Defects in Unstable Crystals: Austenitic Iron

2011 ◽  
Vol 1363 ◽  
Author(s):  
G.J. Ackland ◽  
T.P.C. Klaver ◽  
D.J. Hepburn
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Defect Formation ◽  
Single Layer ◽  
Temperature Limit ◽  
Reference State ◽  
First Principles Calculations ◽  
General Picture ◽  
Bcc Iron ◽  
Defect Energies

ABSTRACTFirst principles calculations have given a new insight into the energies of point defects in many different materials, information which cannot be readily obtained from experiment. Most such calculations are done at zero Kelvin, with the assumption that finite temperature effects on defect energies and barriers are small. In some materials, however, the stable crystal structure of interest is mechanically unstable at 0K. In such cases, alternate approaches are needed. Here we present results of first principles calculations of austenitic iron using the VASP code. We determine an appropriate reference state for collinear magnetism to be the antiferromagnetic (001) double-layer (AFM-d) which is both stable and lower in energy than other possible models for the low temperature limit of paramagnetic fcc iron. Another plausible reference state is the antiferromagnetic (001) single layer (AFM-1). We then consider the energetics of dissolving typical alloying impurities (Ni, Cr) in the materials, and their interaction with point defects typical of the irradiated environment. We show that the calculated defect formation energies have fairly high dependence on the reference state chosen: in some cases this is due to instability of the reference state, a problem which does not seem to apply to AFM-d and AFM-1. Furthermore, there is a correlation between local free volume magnetism and energetics. Despite this, a general picture emerge that point defects in austenitic iron have geometries similar to those in simpler, non-magnetic, thermodynamically stable FCC metals. The defect energies are similar to those in BCC iron. The effect of substitutional Ni and Cr on defect properties is weak, rarely more than tenths of eV, so it is unlikely that small amounts of Ni and Cr will have a significant effect on the radiation damage in austenitic iron at high temperatures.

scholarly journals Linear-Response Calculations of Electron-Phonon Coupling Parameters and Free Energies of Defects

1995 ◽  
Vol 408 ◽  
Author(s):  
Andrew A. Quong ◽  
Amy Y. Liu
Keyword(s):  
Linear Response ◽  
Harmonic Approximation ◽  
Linear Response Theory ◽  
Real Space ◽  
Vibrational Properties ◽  
Phonon Coupling ◽  
Free Energies ◽  
Electron Phonon Coupling ◽  
Coupling Parameters ◽  
Average Electron

AbstractLinear-response theory provides an efficient approach for calculating the vibrational properties of solids. Moreover, because the use of supercells is eliminated, points with little or no symmetry in the Brillouin zone can be handled. This allows accurate determinations of quantities such as real-space force constants and electron-phonon coupling parameters. We present highly converged calculations of the spectral function α2F(ω) and the average electron-phonon coupling for Al, Pb, and Li. We also present results for the free energy of vacancy formation in Al calculated within the harmonic approximation.

On the Statistics of Many Interacting Waves far from Thermal Equilibrium

1973 ◽  
Vol 28 (5) ◽  
pp. 762-771 ◽  
Author(s):  
W. Wonneberger ◽  
J. Lempert
Keyword(s):  
Distribution Function ◽  
Thermal Equilibrium ◽  
Specific Interaction ◽  
Photon Counting ◽  
Interaction Model ◽  
Stationary Waves ◽  
Thermal Waves ◽  
Small Frequency ◽  
Individual Wave ◽  
Counting Distribution

The intensity distribution function P(I) for the incoherent superposition of interacting stationary waves far from thermal equilibrium and coupled to many other waves e. g. in active photon and phonon systems is determined analytically for a specific interaction model. The model consists of Nm ⪢ 1 equivalent waves concentrated in a small frequency band which interact through their intensities alone. P{I) refers to Nm′′＜ Nm of these waves. The remaining Nm′=Nm-Nm′′ waves then act as a reservoir. P(l) is shown to be asymptotically given by a Beta-distribution for Nm′⪢ 1. It is found that the interactions thermalize each individual wave which otherwise would be laser like concerning its statistical properties. The photon counting distribution associated with P(l) is also discussed. For Nm′′ comparable to Nm , it can differ significantly from the photon counting distribution of Nm′′ independent thermal waves.

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