| Silicon is the most widely used semiconductor material in microelectronic devices. Since silicon-based nanomaterial has very different optical and electrical propertieswith bulk silicon material, it can be used in a variety of nanoscale devices. In this article, we mainly studied hydrogenated amorphous silicon (a-Si:H) film, nanocrystalline silicon (nc-Si)film, hydrogenated amorphous silicon carbide (a-Si1-xCx:H) film and silicon nanowires (SiNWs). An in situ study of crystallization process from hydrogenated amorphous silicon film to nanocrystalline silicon film was conducted, as well as the microstructure and properties of hydrogenated amorphous silicon carbide film and silicon nanowire.In this work, silicon-based materials were prepared via plasma enhanced chemical vapor deposition. Silane and hydrogen were used as thereaction sources.The main research findings are summarized as follows:l.The nanocrystalline structural characteristics have been well proven to influence various crucial functionalities of nc-Si films. For the first time, the crystallization phenomenon from amorphous silicon film to nanocrystalline silicon film was visualizedinsitu at an atomic level using environmental transmission electron microscope. We confirm that the formation of nc-Si films includes five main steps: embryos formed in a flashing manner, small stable nucleus formation, grain orientation, the grain coalescence and further growth. This study is useful to the future research for the rational-designed nanocrystalline materials.2. A range of a-Si1-xCx:H thin films prepared using plasma enhanced chemical vapor deposition (PECVD) were annealed at different temperature. It was found that the content of Si-Hn group and C-Hn group decreased with the increased temperature from200℃to600℃, and more Si-C bonds and sp3hybridized C clusters were formed. Such atomic bonding configuration variation was found to induce enlarged optical band gap. In addition, the PL wavelength was effectively adjusted, and its efficiency was significantly enhanced. The underlying relationship between the atomic bonding characteristics and the optical properties of a-Si1-xCx:H was extensively discussed.3. Silicon nanowires directly grown on TCO were investigated. Experimental results showed that the length of the growing Si nanowires increased when silicon nanowires prepared at higher substrate temperatures.Meanwhile, the crystallinity of the silicon material increased with increasing substrate temperature first, and then decreased. At a substrate temperature of500℃, the crystallization of nanocrystalline silicon films was36.8%. At other experimental temperature the film was characterized as amorphous. Further, when the substrate temperature was higher, there were more elongated silicon nanowires, and since their surface area increased and the density was more compact, they have higher light absorption, and thus had more potential as a material for producing solar cells. |
