Amorphous Si films are generally deposited on glass by physical or chemical vapor deposition. When annealed, they undergo crystallization through nucleation and grain growth. At low annealing temperatures, crystallization starts near the glass substrates for pure Si films and near metals for metal-induced crystallization. In this case, crystallites grow along the <111> directions of c-Si nearly parallel to the film plane, that is, the directed crystallization. The directed crystallization is likely to develop the <110> or <111> orientation, which means the <110> or <111> directions are along the film thickness direction. As the annealing temperature increases, equiaxed crystallization tends to increase, which in turn increases random orientation. When the annealing temperature is further increased, the <111> orientation may be obtained.