On-lattice kinetic Monte Carlo simulations of defects migration in silicon: The effects of temperature and recombination distance

Date

2011

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Darwin B. Putungan

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Abstract

An on-lattice kinetic Monte Carlo (kMC) simulation was devised to investigate defects migration in pure crystalline silicon. The kMC method was based on the Bortz- Kalos-Lebowitz (BKL) algorithm where rates of all events were updated depending on the degree of their probable occurrence. A migration square lattice of size 100x100 was initialized with randomly distributed intrinsic point defects. Intrinsic point defects include vacancies and interstitials. A vacancy is a lattice site where an atom is missing while an interstitial is an atom that is located in a non-equilibrium position of a lattice. The vacancies and interstitials were isotropically diffused in its von Neumann’s neighborhood and were recombined depending on the input recombination distance. The energy barriers (Tang, Phys. Rev. B. 1997) of vacancies and self-interstitials that were used are 0.1 eV and 1.37 eV, respectively. The parameters that were varied are temperature (298K, 500K, 1000K, and 1500K) and recombination distance (4Å, 8Å, 12Å and 16Å). At higher temperatures, the fraction of surviving defects has decreased at greater rates and, hence, at shorter times. Similarly, when the recombination distance of defects was increased, the fraction of surviving defects had decreased at a faster rate. In effect, faster annihilation of defects was observed at increasing temperature or at increasing recombination distance. Also, when the effect of temperature was compared with that of recombination distance, the time evolution of the fraction of surviving defects had indicated that recombination takes place at a faster rate in systems with increased temperature than in systems with increased recombination distance. Hence, the survival of point defects was greatly affected by the variation in temperature as compared to the variation in the recombination distance. In addition, at low temperatures, vacancies have greatly contributed to the self-diffusion of silicon while at extremely high temperatures, interstitials have dominated the diffusion process.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Document Type

Thesis

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