Self-Induced Preparation of Assembled Shrubbery TiSi Nanowires by Chemical Vapor Deposition

Abstract

We report a new self-induced catalyst-free method for the preparation of shrubbery TiSi nanowires by atmospheric pressure chemical vapor deposition. SiH 4 and TiCl 4 are used as a silicon precursor and titanium precursor, respectively. Ti 5 Si 3 thin films are formed initially, and then one-dimensional TiSi nanostructures are grown on top of the thin films. A novel, assembled structure with electrically conductive shrubbery TiSi nanowires with an electrically conductive Ti 5 Si 3 thin layer underneath is finally obtained. The TiSi nanowires grow along the direction perpendicular to the (110) plane of the orthorhombic TiSi crystal. The nanowires are more than 5 μm long, and their diameters are about 15−40 nm. With the flux of (SiH 4 + TiCl 4 ) reaching values larger than 35 sccm or increasing from 20 to 35 sccm, the quantities of TiSi nuclei are increased and, thus, the TiSi nanowire bundles and rocket-shaped nanowires are also successfully prepared, respectively. With regard to producing a high storage capacitor with the nanowire bottom electrode embedded within the dielectric thin film of Ba 0.6 Sr 0.4 TiO 3 (BST), the capacitance of the BST/assembled-nanowire-electrode complex structure is about 28 pF, which is approximately 3 times higher than that of BST deposited on indium-tin oxide (ITO). This creates a new way to fabricate the thin film devices with a high storage capacitance.