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Title: Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide

Abstract

The thermal stability of an antisite pair in 3C-SiC is studied using ab initio molecular dynamics within the framework of density functional theory. The lifetime of the antisite pair configuration is calculated for temperatures between 1800 and 2250 K, and the effective activation energy for antisite pair recombination is determined to be 2.52 eV. The recombination energy path and static energy barrier are also calculated using the nudged elastic band method, along with the dimer method to accurately locate the transition states. The consistency of the results suggests that the antisite pair cannot be correlated with the DI photoluminescence center, as proposed by previously theoretical interpretations. An extended exchange mechanism is found for the antisite pair recombination, and this may be a dominant mechanism for antisite pair recombination and diffusion of impurities in compound semiconductors.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
909462
Report Number(s):
PNNL-SA-55091
Journal ID: ISSN 0003-6951; APPLAB; 8208; KC0201020; TRN: US200722%%1093
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters, 90(22):Art. No. 221915; Journal Volume: 90; Journal Issue: 22
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SILICON CARBIDES; ELECTRONIC STRUCTURE; CARBON; COMPOSITE MATERIALS; MOLECULAR DYNAMICS METHOD; DENSITY FUNCTIONAL METHOD; ACTIVATION ENERGY; PHOTOLUMINESCENCE; RECOMBINATION; Ab initio calculation; Antisite defects; annealing behavior; Silicon Carbide; Environmental Molecular Sciences Laboratory

Citation Formats

Gao, Fei, Du, Jincheng, Bylaska, Eric J., Posselt, Matthias, and Weber, William J. Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide. United States: N. p., 2007. Web. doi:10.1063/1.2743751.
Gao, Fei, Du, Jincheng, Bylaska, Eric J., Posselt, Matthias, & Weber, William J. Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide. United States. doi:10.1063/1.2743751.
Gao, Fei, Du, Jincheng, Bylaska, Eric J., Posselt, Matthias, and Weber, William J. 2007. "Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide". United States. doi:10.1063/1.2743751.
@article{osti_909462,
title = {Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide},
author = {Gao, Fei and Du, Jincheng and Bylaska, Eric J. and Posselt, Matthias and Weber, William J.},
abstractNote = {The thermal stability of an antisite pair in 3C-SiC is studied using ab initio molecular dynamics within the framework of density functional theory. The lifetime of the antisite pair configuration is calculated for temperatures between 1800 and 2250 K, and the effective activation energy for antisite pair recombination is determined to be 2.52 eV. The recombination energy path and static energy barrier are also calculated using the nudged elastic band method, along with the dimer method to accurately locate the transition states. The consistency of the results suggests that the antisite pair cannot be correlated with the DI photoluminescence center, as proposed by previously theoretical interpretations. An extended exchange mechanism is found for the antisite pair recombination, and this may be a dominant mechanism for antisite pair recombination and diffusion of impurities in compound semiconductors.},
doi = {10.1063/1.2743751},
journal = {Applied Physics Letters, 90(22):Art. No. 221915},
number = 22,
volume = 90,
place = {United States},
year = 2007,
month = 5
}
  • The authors present first-principles calculations of the structural, lattice dynamical, and thermal properties as well as Raman results for cubic silicon carbide (3C SiC). The plane-wave pseudopotential approach to density functional theory (DFT) in the local density approximation has been used to calculate the equilibrium properties of 3C SiC, i.e., the ground-state energy, the band structure, the valence electron density, the lattice constant, the bulk modulus, its pressure derivative, and the ionicity factor of the chemical bonds. The linear-response theory within DFT has been used to obtain the phonon frequencies, the eigenvectors, and the mean-square atomic displacements. Furthermore, the authorsmore » calculated the mode Grueneisen parameters, the internal-strain parameter, the elastic constants, the Born effective charge, and the high-frequency dielectric constant. The specific heat at constant volume and at constant pressure, the thermal expansion coefficient, the temperature dependence of the lattice constant, and that of the isothermal and adiabatic bulk modulus have been derived within the quasi-harmonic approximation. Finally, the second-order Raman spectrum of 3C SiC has been calculated using phenomenological polarizability coefficients and ab initio frequencies and eigenvectors. 66 refs., 17 figs., 5 tabs.« less
  • Scanning tunneling microscopy (STM) images of the cubic [beta]-SiC(100) and [beta]-SiC(111) surfaces are taken after annealing to 1,200C to eliminate the surface oxide. Low-energy electron diffraction (LEED) patterns of the [beta]-SiC(111) surface show a 6[radical] x 6[radical]3 geometry, while STM images show a 6 x 6 geometry. Contrast reversal is observed as tunneling voltage bias is reversed. Spectroscopic I/V measurements indicate the presence of a graphite layer on the top surface. A model of the surface is proposed where an incommensurate graphite monolayer is grown over a (1 x 1) Si-terminated [beta]-SiC(111) surface. This model helps to explain the discrepancymore » between the 6[radical]3 x 6[radical]3 LEED pattern and the 6 x 6 geometry observed in STM images. Charge transfer between certain carbon atoms and silicon atoms gives rise to the 6 x 6 geometry and the contrast reversal.« less
  • The thermal stability of the first-neighbor antisite pair configurations in 3C- and 4H-SiC is investigated by a comprehensive atomistic study. At first the structure and energetics of these defects is determined in order to check the accuracy of the Gao-Weber interatomic potential used. The results are comparable with literature data obtained by the density-functional theory. Then, the lifetime of the antisite pair configurations is calculated for temperatures between 800 and 2500 K. Both in 3C- and 4H-SiC the thermal stability of the antisite pairs is rather low. In contrast to previous theoretical interpretations, the antisite pair can be therefore notmore » correlated with the DI photoluminescence center that is stable to above 2000 K. The atomic mechanisms during the recombination of the antisite pair in 3C-SiC and of three antisite pair configurations in 4H-SiC is a modified concerted exchange. Due to the different sizes of the silicon and the carbon atoms, this process is not identical with the concerted exchange in Si. Two intermediate metastable configurations found during the recombination are similar to the bond defect in Si. Since the SiC lattice contains two types of atoms, there are also two different types of bond defects. The two bond defects can be considered as the result of the incomplete recombination of a carbon vacancy and a neighboring mixed dumbbell interstitial. For selected temperatures the thermal stability of the antisite pair in 3C-SiC is investigated by molecular dynamics simulations that are based on the density-functional theory. Their results are very similar to those of the atomistic study, i.e. the Gao-Weber potential describes the antisite pair and its recombination reasonably well. The antisite pair in 4H-SiC with the two atoms on hexagonal sites has a slightly different formation energy than the other three antisite pair configurations in 4H-SiC. Its lifetime shows another dependence on the temperature, and its recombination is characterized by a separate motion of atoms.« less