Structural characterization and crystallization process of nanostructured silicon thin films produced in low-pressure silane plasma

Nanostructured silicon thin films (ns-Si:H), consisting of a two-phase mixture of amorphous and ordered material, were obtained by plasma-enhanced chemical vapor deposition (PECVD) under a wide range of plasma conditions. The key to embedding Si-ordered particles in the amorphous Si matrix was the formation of silicon clusters in the gas phase (diameter <2 nm) under conditions of plasma polymerization, and their incorporation into the growing films. The crystallization induced by thermal annealing in these nanostructured films can be attained faster than in conventional a-Si:H thin films, because the silicon-ordered particles cause a heterogeneous nucleation process in which they act as seeds for crystallization. In this work, we present a detailed structural characterization by using electron and X-ray diffraction patterns and Raman spectroscopy. The crystallization dynamics were studied in-situ by Raman spectroscopy.