Ab initio study of fluorine in silicon: large clusters and the dominant mobile defect.
We determine the dominant mobile fluorine defect in silicon by density-functional based simulations. Among the mobile defects FV2, FV, F, and FI, we find the extra fluorine atom (F) to dominate diffusion. In p-type silicon it is neutral and in n-type silicon it is negatively charged. The calculated concentration of this defect is by a factor of at least 10(6) higher compared to the other mobile defects. During migration of both F0 and F- the fluorine atom moves from one bond-centered configuration into a neighboring one. For the negatively, neutral, and positively charged mobile defects the relative mobility was determined by molecular dynamics simulations at a temperature of 1000 degrees C. Defect concentrations were derived from calculated cluster formation energies for a large number of clusters.
Integrated Systems Laboratory, ETH Zurich, Gloriastrasse 35, Zurich 8092, Switzerland.
Kilian
K
Vollenweider
Beat
B
Sahli
Wolfgang
W
Fichtner