Correlation factors for interstitial-mediated self-diffusion in the diamond lattice: Kinetic lattice Monte Carlo approach

Abstract

We have performed extensive analysis of the correlation factors for interstitial-mediated self-diffusion via various possible mechanisms and hopping networks in the diamond lattice using the kinetic lattice Monte Carlo approach. The correlation factor for the kick-out mechanism in the tetrahedral hopping network is calculated to be 0.73, in agreement with previous results; and the value for the hexagonal hopping network is 0.47 for the dominant mechanism. For the mechanism where a split interstitial is stable (``stable-split'' mechanism), the correlation factor for the tetrahedral network stays the same while that for the hexagonal network increases to 0.62. We then performed simulations for the diffusion process of silicon involving multiple mechanisms. The choice of mechanisms is justified by ab initio calculations. We conclude that unlike vacancy diffusion, interstitial self-diffusion has a temperature-dependent correlation factor. This conclusion holds in general for diffusion processes involving multiple mechanisms with different activation energies. The correlation factor obtained from ab initio results for interstitial-mediated self-diffusion in silicon at 1000--1100 \ifmmode^\circ\else\textdegree\fi{}C is 0.64--0.80, compared to the value of 0.6 extracted from the experiment.