Tight-binding molecular dynamics study of vacancy-interstitial annihilation in silicon

Abstract

We have studied the annihilation of a tetrahedral interstitial by a vacancy using molecular dynamics and a tight-binding model due to Goodwin-Skinner-Pettifor. At both 1473 and 1173 K, the annihilation process was dominated by the movement of the faster-diffusing vacancy. Once the vacancy moved to a nearest-neighbor position relative to the interstitial, annihilation was inevitable. As the initial distance between the T-interstitial and the vacancy increased, the number of pathways by which annihilation occurs increased accordingly. Fast and slow annihilation pathways were identified. The process was found to be highly stochastic in nature, requiring multiple simulations to provide adequate statistics. System size was not a factor in altering the results. The capture radius, within which annihilation is assured, was found to be between 5-6 Å at 1473 K, although it is clear from the orientation dependence of the results that a spherically symmetric view of the capture radius is somewhat inappropriate. Limited investigation of annihilation between a ͑110͒ split interstitial and a vacancy confirmed the basic results of Tang et al. ͑Ref. 21͒ ͑using a Kwon tight-binding model͒ that the formation of a double-vacancy: double-interstitial configuration, dubbed a ''bond-defect'' by those authors, occurs in some but not all cases as part of the annihilation mechanism.

Theoretical determination of stable fourfold coordinated vacancy clusters in silicon

“…[8][9][10][11] Small vacancy defects have been of particular interest because they are a main source or a getter for mobile vacancies and interstitials, which are largely responsible for dopant transient enhanced diffusion and electrical deactivation in ultrashallow junction formation for Si-based electronic devices. [12][13][14][15][16][17] Previous theoretical studies [18][19][20][21] proposed "part of hexagonal ring" ͑PHR͒ and spherically shaped cluster ͑SPC͒ models for the structure of vacancy clusters. According to the models, the V 6 , V 10 , and V 14 PHR configurations are predicted to be particularly stable because of their relatively reduced number of Si-Si broken bonds.…”

Role of configurational entropy in the thermodynamics of clusters of point defects in crystalline solids

“…7 possess energies that are higher than a completely dissociated cluster, even though they represent valid Stillinger clusters. These configurations correspond to the formation of additional defect structures such as Frenkel pairs ͑interstitial-vacancy pairs͒ 34 and other types of disordered states, and suggest a mechanism for amorphization and even crystal melting.…”

(Invited) Computer Simulation of Intrinsic Point Defect Distribution Valid for All Pulling Conditions in Large-Diameter Czochralski Si Crystal Growth

“…Tight-binding molecular dynamics (MD) studies were performed for pair recombination in Si (19,20). It was found that the energy barrier for pair recombination varies between 0 and 1.1 eV depending on the V-I distance and also the site of I.…”