Molecular dynamics and quasidynamic simulations of low-energy particle bombardment effects during vapour-phase crystal growth: 10–50 eV Si and In atoms incident on (2 × 1)-terminated Si(001)

Abstract

Molecular dynamics and quasidynamic simulations, utilizing the Tersoff many-body potential, were used to investigate projectile incorporation and defect production as well as lattice relaxation, diffusion, and annihilation of defects resulting from 10 and 50 eV Si and In irradiation of (2 × 1)-terminated Si(001). Due to the extreme deference in the time scales associated with the collision cascade and atom diffusion, the two cases were treated separately. Ion-assisted epitaxy, In incorporation into near-surface lattice sites, interstitial and vacancy formation, and position exchange reactions were observed. The stabilized structures of interstitials and vacancies together with pathways and activation energies for Si and In diffusion were calculated as a function of depth below the surface. Near-surface interstitials were found to be easily annealed at typical Si growth temperatures. However, residual vacancies, present at much lower concentrations, are much more difficult to anneal out. Near-surface In atoms were found to exhibit large driving forces for surface segregation. Preventing In segregation during Si growth at 500 °C required the In ions to penetrate to at least the third layer.