Unstable Stacking Fault Free Energies In Silicon Through Empirical Modeling

Abstract

The temperature dependence of unstable stacking fault free energies on glide and shuffle {111} planes in silicon is investigated using a finite temperature molecular dynamics approach which includes a full treatment of anharmonic vibrational effects. The results are compared to earlier zero temperature ab initio calculations in which finite temperature effects were estimated using a harmonic approximation to transition state theory (TST). The unstable stacking free energies are interpreted within the framework of Rice's dislocation nucleation criterium to characterize a possible change from shuffle to glide plane dominance in the context of dislocation nucleation processes at a sharp crack tip. Such a change may be related to the abrupt brittle-ductile transition observed in silicon.539175180Samuels, J., Roberts, S.G., (1989) Proc. R. Soc. London A, 421, p. 1Hirsch, P.B., Roberts, S.G., Samuels, J., (1989) Proc. R. Soc. London A, 421, p. 25Hirth, J.P., Lothe, J., (1982) Theory of Dislocations, , Wiley, New YorkRice, J.R., (1992) J. Mech. Phys. Solids, 40, p. 239Rice, J.R., Beltz, G.E., (1994) J. Mech. Phys. Solids, 42, p. 333Sun, Y., Beltz, G.E., (1993) Mater. Sci. Eng., A170, p. 67Kaxiras, E., Duesbery, M.S., (1993) Phys. Rev. Lett., 70, p. 3752Juan, Y.-M., Kaxiras, E., (1996) Phil. Mag. A, 74, p. 1367Vineyard, G.H., (1957) J. Phys. Chem. Solids, 3, p. 121Bazant, M.Z., Kaxiras, E., Justo, J.F., (1997) Phys. Rev. B, 56, p. 8542Justo, J.F., Bazant, M.Z., Kaxiras, E., Bulatov, V., Yip, S., (1998) Phys. Rev. B, 58, p. 2539De Koning, M., Antonelli, A., (1996) Phys. Rev. E, 53, p. 465De Koning, M., Antonelli, A., (1997) Phys. Rev. B, 55, p. 73