Gold catalyzed nickel disilicide formation: a new solid-liquid-solid phase growth mechanism

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• The vapor-liquid-solid (VLS) mechanism is the primary method for semiconductor nanowire (NW) growth.
• Understanding alternative growth mechanisms is crucial for advancing NW fabrication.

Purpose of the Study:

• To report and characterize a novel solid-liquid-solid (SLS) growth mechanism for silicide phases in silicon nanowires (Si NWs).
• To elucidate the fundamental differences in nucleation and mass transport compared to the VLS mechanism.

Main Methods:

• In situ transmission electron microscopy (TEM) for real-time observation of the growth process.
• In situ quenching experiments to measure solubility in the ternary alloy.
• Analysis of atomic diffusion and nucleation within a liquid-mediating layer.

Main Results:

• A new SLS growth mechanism for Ni disilicide (NiSi2) in Si NWs was identified.
• Ni atoms diffuse interstitially through the Si NW to a liquid alloy seed.
• NiSi2 nucleation occurs within the liquid alloy, followed by NW transformation and sweeping.

Conclusions:

• The SLS mechanism provides a distinct pathway for silicide formation in Si NWs, differing from VLS in nucleation and mass transport.
• The Au-catalyzed SLS process can reduce NiSi2 formation temperature by 100 °C compared to solid-state reactions.
• This discovery offers new possibilities for low-temperature synthesis of silicides in nanostructures.