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

Continuous-wave laser ablation of an SiO target was performed to grow nanowires (NWs) in high-pressure (up to 0.90 MPa) Ar, N2, and O2 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 SiOx and attached with sphere-like nanoparticles (NPs) at their tips. The tip NPs were composed of crystalline Si covered with thin amorphous SiOx layers. Similar NW growth occured in N2 gas. However, only amorphous NPs were generated in O2 gas. On the basis of liquid-like molten SiOx NPs containing a portion of a Si phase formed by a disproportionation reaction of SiOx, we discuss the nucleation and growth of the NWs through supersaturation and anisotropic precipitation of SiOx.