Crystallization of amorphous Si films by pulsed laser annealing and their structural characteristics

Abstract

Nanocrystalline silicon (nc-Si) films were prepared by pulsed laser annealed crystallization of amorphous silicon (α-Si) films on SiO2-coated quartz or glass substrates. The effect of laser energy density on structural characteristics of nc-Si films was investigated. The Ni-induced crystallization of the α-Si films was also discussed. The surface morphology and microstructure of these films were characterized by scanning electron microscopy, high-resolution electron microscopy, atomic force microscopy and Raman scattering spectroscopy. The results show that not only can the α-Si films be crystallized by the laser annealing technique, but also the size of Si nanocrystallites can be controlled by varying the laser energy density. Their average size is about 4–6 nm. We present a surface tension and interface strain model used for describing the laser annealed crystallization of the α-Si films. The doping of Ni atoms may effectively reduce the threshold value of laser energy density to crystallize the α-Si films, and the flocculent-like Si nanostructures could be formed by Ni-induced crystallization of the α-Si films.