Improved control of silicon nanowire growth by the vapor–liquid–solid method using a diffusion barrier layer between catalyst and substrate

Vapor–liquid–solid (VLS)-grown nanowires are promising building blocks for next-generation devices because of their unique characteristics. Although Au is a widely used catalyst with the largest operable parameter window for Si nanowire growth by the VLS method, Au catalyst droplets diffuse at a high migration velocity over a Si substrate surface and agglomerate at relatively low temperature, thus degrading the uniformity of Au catalyst droplets and Si nanowires. Our aim is to improve the controllability of nanowire growth, positioning, and diameter, which are essential attributes for practical applications. To accomplish this, a diffusion barrier layer was inserted between the catalyst and substrate. Length and diameter uniformity were considerably improved for nanowires grown together with the formation of a silicide layer as a diffusion barrier.

► A diffusion barrier was inserted beneath the catalyst for VLS nanowire growth.
► The surface diffusion of the Au catalyst was suppressed during the nucleation step.
► The length and diameter uniformities were considerably improved.
► The grown nanowires exhibited epitaxial growth in a controlled direction.