Catalytic syntheses of silicon nanowires and silica nanotubes

Silicon nanowires (SiNWs) have been fabricated with metal- and SiO₂-catalyses assisted by laser ablation. In the growths of single-crystalline SiNWs by metal-catalysts, it is found that SiNWs are along <111> growth direction; however, the <112> growth direction is resulted in the SiO₂-catalyzed SiNWs. Pressure effect on the longitudinal and transverse growing rates of these SiNWs has also been examined. With the chemical vapor deposition method, the silica nanotubes (SiO₂NTs) could be achieved with Au nanoparticles as catalysts. From electron diffraction pattern, it shows that the SiO₂NTs are amorphous and the possible growth mechanism would be discussed.