Thermal Stability of Metal-Catalyzed Silicon Nanowires

Ted Kamins, Xuema Li, and R. Stanley Williams
Hewlett-Packard Laboratories, US

Keywords: silicon, nanowires, stability, diffusion

Abstract:
Si nanowires have been suggested as components of future nanoelectronic devices. Using Si offers the possibility of integration with conventional IC technology and fabrication equipment, especially if the catalyzing nanoparticle is also compatible. The stability of the wires during subsequent heat treatments is not widely known; therefore, the stability of the wires has been investigated and is reported here. Si wires were formed by catalytic growth by chemical vapor deposition on Ti nanoparticles at approximately 590°C using silane in a hydrogen ambient. After growth, the wires were heated in a hydrogen ambient without intermediate air exposure. At temperatures up to ~850°C for 1 h, little change is seen in the wire shape, even without a stabilizing native oxide layer, demonstrating the stability of the wires. However, after heating to ~900°C for 1 h, significant changes are visible in the wires. Rather than having a diameter that varies continuously along the wire, the diameter often appears to vary discontinuously. In some cases, the diameter decreases in several discrete steps along the length of the wire and remains relatively constant between steps. The stepped surface is consistent with surface diffusion of Si atoms to form larger terraces and higher steps.

NSTI Nanotech 2003 Conference Technical Program Abstract