Molecular-dynamics simulations of solid phase epitaxy in silicon: Effects of system size, simulation time, and ensemble

摘要

Solid phase epitaxial (SPE) recrystallization of amorphous Si on a Si(001) substrate was examined by large-scale (6144-129024 Si atoms), long-time (up to 2000 ns) molecular-dynamics (MD) simulations using the empirical Tersoff interatomic potential. We particularly focused on the effects of the MD cell size, simulation time, and ensemble on the SPE growth rate. We found that the simulations under the isothermal-isochoric conditions (M/Tenserrible) show a higher crystallization rate than those under the isothermal-isobaric conditions (NPTensemble). The system size dealt with in the present MD simulation, i.e., 6144 Si atoms, was enough to estimate the SPE growth rate. The Arrhenius plot of the growth rate between 1300 and 1600 K exhibited a single activation energy, similar to 2.4 eV, which is in agreement with the experimental value (similar to 2.7 eV). However, the growth rate at temperatures below 1300K deviated from the extrapolated ones from 1300 to 1600K, which is because recrystallization does not reach a steady state: long-time MD simulations are required to estimate the growth rate at low temperature. The structure analysis of amorphous/crystalline interfaces suggested that the braking of atomic bonds parallel to the interface becomes a rate-limiting step of the SPE growth. (C) 2018 The Japan Society of Applied Physics