Optical and structural features of silicon-rich hydrogenated amorphous silicon nitride thin films.

A systematic study of fabrication and effect of post-deposition processing on the optical and structural features of silicon-rich hydrogenated amorphous silicon nitride thin films deposited by Hg-sensitized Photo-Chemical Vapour Deposition technique is presented. Both deposition parameters and post-deposition thermal treatment resulted into substantial change in the refractive index associated with the densification of the film. Our studies reveal that the presence of hydrogen and its out-diffusion upon thermal treatment play a crucial role in the overall structural evolution, specially the stabilization of individual phases such as Si and Si3N4. We further report the room-temperature photoluminescence from as-deposited films, which is due to formation of silicon nanostructures in crystalline and amorphous forms. These studies are of great interest from the prospective of commercially viable Si-based technology.

Phase stabilization by rapid thermal annealing in amorphous hydrogenated silicon nitride film.

We have studied the effect of rapid thermal annealing (RTA) in the context of phase evolution and stabilization in hydrogenated amorphous silicon nitride (a-SiN(x):H) thin films having different stoichiometries, deposited by an Hg-sensitized photo-CVD (chemical vapor deposition) technique. RTA-treated films showed substantial densification and increase in refractive index. Our studies indicate that a mere increase in flow of silicon (Si)-containing gas would not result in silicon-rich a-SiN(x):H films. We found that out-diffusion of hydrogen, upon RTA treatment, plays a vital role in the overall structural evolution of the host matrix. It is speculated that less incorporation of hydrogen in as-deposited films with moderate Si content helps in the stabilization of the silicon nitride (Si(3)N(4)) phase and may also enable unreacted Si atoms to cluster after RTA. These studies are of great interest in silicon photonics where the post-treatment of silicon-rich devices is essential.

Structural phase transition study of the morphotropic phase boundary compositions of Na(0.5)Bi(0.5)TiO(3)-PbTiO(3).

Neutron, synchrotron x-ray powder diffraction and dielectric studies have been performed for morphotropic phase boundary (MPB) compositions of the (1-x)Na(1/2)Bi(1/2)TiO(3)-xPbTiO(3) system. At room temperature, the MPB compositions (0.10