Controlling the nucleation site and crystal orientation during eximer-laser annealing processes in thin amorphous Si films on glass: A molecular-dynamics study

We propose a new technique to control the nucleation site and crystal orientation for obtaining large poly-Si grains with the (001) surface during eximer-laser annealing processes of amorphous Si films on glass based on molecular dynamics (MD) simulations. Preferential nucleation sites of supercooled melted Si can be controlled at the top parts of nano-scale reverse-pyramidal pits on glass by setting a proper temperature-gradient in the vertical direction of the glass substrate. MD simulations indicate that the nano-structured glass surface must be modified as a chemically inactive wall to melted Si, otherwise a large interfacial energy between Si and SiO₂ prevents nucleation at the pyramidal interface where the Si(111) surface is generated. It is also found that {111} stacking faults are sometimes formed. We suggest that this {111} stacking fault formation can be avoided by utilizing low-temperature solid-phase-epitaxial growth of Si where crystallization tends to proceed along the amorphous/crystal Si(001) interface.