Molecular-dynamics simulations of epitaxial crystal growth from the melt. II. Si(111)

Abstract

Molecular-dynamics simulations are employed in studies of liquid-phase epitaxial growth onto a Si(111) surface. The material is described using two- and three-body interaction potentials which provide a realistic description of crystalline silicon and of the crystal-melt interface. From equilibrium solid-melt coexistence, the system is driven out of equilibrium by allowing heat conduction to the underlying substrate. Two heat-extraction rates are used, resulting in growth velocities of 14 and 9 m/sec. The crystal grown under the faster growth conditions contains stacking faults, defective layers, and an amorphous region. The slower growth results in a more perfect crystal with stacking faults and a narrow region of disorder at the solid-vacuum interface. Crystallization is initiated when the crystal-melt interface supercools by ∼150 K and a layer-by-layer growth mode is observed, accompanied by self-annealing processes. The dynamics of the crystal-growth processes are investigated with refined spatial and temporal resolution using real-space particle trajectories and following the evolution of the system temperature, potential-energy, and density profiles.