Preparation Of Silicon Nanowires And Nanotubes And Study On Physical Property

In this world, One-dimensional silicon nanomaterial has been paid widespread attention for its unique optical, electrical and semiconductor property, and it has become one of the research focus of nano-scientist, same as carbon nanotubes. Because of being compatible with the modern microelectronics industry, silicon nanowires and silicon nanotubes is expected to be successful in the field of nano-microelectronic devices application, as a new type of low-dimensional semiconductor nanomaterials. The silicon element with SP3hybrid is easy to form a linear structure, so the synthesis of silicon nanotubes is very difficult. At this moment study of silicon nanotubes is still at an early stage. In this paper, with a new chemical reaction method, silicon nanowires and silicon nanotubes were successfully prepared in a simple process, and the composition, structure, growth mechanism and optical properties were researched.Using SiCl4as silicon source and Zn as agent, with no any catalyst and template, silicon nanotubes and silicon nanowires was successfully prepared through a simple chemical reaction between SiCl4and Zn in autoclave. Through XRD, HRTEM, FESEM, EDS, the composition and morphology of silicon nanowires and silicon nanotube were characterized, the result shows that most of the product was the face-centered cubic silicon, and there is also a small amount of amorphous structure. Silicon nanowires and nanotubes with500nm to1μm in length,30-50nm in diameter grew vertically on a thin-walled hollow sphere, part of the matrix was destructed in the process, surface of nanowires and nanotubes was smooth, and the direction of growth was homogeneous. The result of selected area electron diffraction showed the amorphous structure. According to nitrogen adsorption-desorption isotherm and DFT curve analysis, distribution of pore size was2.4nm and5.1nm, specific surface area145.003m2/g.Process reaction temperature, holding time and reactant ratio were analyzed. The results showed that the reaction temperature was important to the growth of nanowires and nanotubes. It showed that the reaction of SiCl4and Zn has been basically completed in only one hour, and the growth of silicon nanowires and nanotubes was relatively slow. It showed that the proportion of SiCl4has a hold on the formation of the growth substrate. In a word, optimum process of nanowires and nanotubes was that ratio of SiCl4and Zn was1:6, reaction temperature550℃, time5h. On the basis of this experimental process, the growth mechanism of silicon nanowires and nanotubes was provid.SiCl4vapor was reacted on the surface of zinc particles and coated with zinc particles in the end, hindering the continued reaction, which explains the formation of the thin-walled spherical substrate. After the reaction, due to the thermal stress caused by high temperature and surface tension of substrate, the silicon nanoparticles were self-assembled and growed into one-dimensional silicon nanostructures; Also, the formation mechanism of silicon nanotubes was provid.The PL spectra of the product showed a strong peak at388nm is caused by the nanocrystalline in small size. And the weak peak at425nm was related to the nanowires and nanotubes. The CL images at room temperature showed the product has good cathode luminescence property. Raman scattering spectrum showed that the Raman peak appeared red-shift because of nano-size grain, and the peak at596nm and423nm may be caused by internal defects of silicon nanowires and nanotubes.