Silicon-catalyzed growth of amorphous SiO_x nanowires by continuous-wave laser ablation of SiO in high-pressure gas

摘要

Continuous-wave laser ablation of an SiO target was performed to grow nanowires (NWs) in high-pressure (up to 0.90 MPa) Ax, N_2, and O_2 gas. In Ar gas, the fraction of the NWs in deposits was changed significantly by the Ar pressure. As Ar pressure increased, thicker NWs with diameters of up to 80 nm were grown. The NWs were amorphous SiO_x and attached with sphere-like nanoparticles (NPs) at their tips. The tip NPs were composed of crystalline Si covered with thin amorphous SiO_x layers. Similar NW growth occurred in N_2 gas. However, only amorphous NPs were generated in O_2 gas. On the basis of liquid-like molten SiO_x NPs containing a portion of a Si phase formed by a disproportionation reaction of SiO_x, we discuss the nucleation and growth of the NWs through supersaturation and anisotropic precipitation of SiO_x.