Antisite pair recombination in cubic SiC by a concerted exchange mechanism


Antisite pair recombination in cubic SiC by a concerted exchange mechanism

Posselt, M.; Gao, F.; Weber, W. J.

An antisite pair consists of two neighboring atoms on “wrong” lattice sites, namely a Si atom on a C site and a C atom on a Si site. This defect can be formed by irradiation with energetic particles, e.g. during ion implantation doping. Investigations on the thermal stability of the antisite pair are important for electronic and nuclear applications of SiC.
In this work the recombination of an antisite pair is studied by classical molecular dynamics simulations using the interatomic potential developed by Gao and Weber [1]. The formation energy of the antisite pair is calculated and compared with literature data. Then, the lifetime of the defect is determined for the temperatures between 800 and 2500 K, and the effective recombination barrier is estimated. The lifetime for 2000 and 2500 K is compared with the results obtained using ab-initio molecular dynamics simulations. The analysis of atomic rearrangements during recombination shows that the mechanism of the antisite pair recombination is a concerted exchange. Due to the different atomic sizes of Si and C, the concerted exchange mechanism in SiC is not identical to that proposed for silicon [2]. During recombination a number of intermediate defect configurations are observed. Two of them are similar to the bond defect in silicon [3,4]. They can be considered as the result of an incomplete recombination of a carbon vacancy and a C+Si<100> dumbbell interstitial. Therefore, the present work yields not only details of the recombination of the antisite pair but also information about possible mechanisms for antisite pair formation.
[1] F. Gao, W. J. Weber, Nucl. Instr. Meth. B 191 (2002) 504
[2] K. C. Pandey, Phys. Rev. Lett. 57 (1986) 2287
[3] M. Tang, L. Colombo, J. Zhu, T. Diaz de la Rubia, Phys. Rev. B55 (1997) 14279
[4] L. A. Marques, L. Pelaz, J. Hernandez, J. Barbolla, G. H. Gilmer, Phys. Rev. B 64 (2001) 045214

Keywords: SiC; point defects; molecular dynamics

  • Lecture (Conference)
    14th Int. Conf. on Ion Beam Modification of Materials (IBMM 2004), September 5-10, 2004, Monterey, USA

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