Phase transformation mechanisms involved in excimer laser crystallization of amorphous silicon films

We have investigated the phase transformation mechanisms and the resulting microstructures of excimer laser-induced crystallization of amorphous Si films on SiO₂. It is shown that the process can be characterized into two major regimes, based on the dependence of the grain size and the melt duration as a function of the incident energy density. It is found that at the transition between the two regimes, exceedingly large grain-sized polycrystalline films can be obtained. We call this the super lateral growth phenomenon, and propose a model based on liquid-phase regrowth from the residual solid seeds when near-complete melting of the Si film occurs.