High resolution electron microscopy study of nanostructured Ni2Si thin films

By applying High Resolution Electron Microscopy (HREM) and electron diffraction, nanostructure characteristics of Ni2Si thin films grown on Si(100) and Si(111) substrates were studied. On Si(111) substrates the silicide film formation occurs in a textured mode. The grains in this case present predominantly low-angle boundaries as evidenced from a dislocation network along the grain boundaries as well as by the corresponding lattice resolution phase-contrast images and diffraction patterns. Contrary to this, on Si(100) substrates the Ni2Si films do not show texture and the grains are separated by high-angle boundaries. Furthermore, the often discussed question whether grain boundaries in nanocrystalline materials show "frozen gas" or "coarse-grained-like" structures in the present case of Ni2Si thin films can be answered in the sense that no evidence for amorphous boundaries could be observed.