Ledge-flow-controlled catalyst interface dynamics during Si nanowire growth

Abstract

Self-assembled nanowires offer the prospect of accurate and scalable device engineering at an atomistic scale for applications in electronics, photonics and biology. However, deterministic nanowire growth and the control of dopant profiles and heterostructures are limited by an incomplete understanding of the role of commonly used catalysts and specifically of their interface dynamics. Although catalytic chemical vapour deposition of nanowires below the eutectic temperature has been demonstrated in many semiconductor-catalyst systems, growth from solid catalysts is still disputed and the overall mechanism is largely unresolved. Here, we present a video-rate environmental transmission electron microscopy study of Si nanowire formation from Pd silicide crystals under disilane exposure. A Si crystal nucleus forms by phase separation, as observed for the liquid Au-Si system, which we use as a comparative benchmark. The dominant coherent Pd silicide/Si growth interface subsequently advances by lateral propagation of ledges, driven by catalytic dissociation of disilane and coupled Pd and Si diffusion. Our results establish an atomistic framework for nanowire assembly from solid catalysts, relevant also to their contact formation.

Revealing lithium–silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy

“…2). The catalytic NW growth mode [37][38][39] favours a o1114 growth direction, but a range of other crystallographic orientations and defects are also found. Air exposure during post-growth transfer results in the formation of a B2-nm thick native oxide layer surrounding each SiNW.…”

Birth of silicon nanowires covered with protective insulating blanket

“…The formation of the ledge and the growth of the layers are studied by in situ TEM analysis. [19] However, this study was performed on a single element precipitated NW (i.e., Si). Such a growth process cannot be related to the growth observed here since two different nuclei (Si and SiO x ) should join to form a ledge centered with Si atoms that potentially match with the new layers formed on the top.…”

Nanosize effect in Germanium Nanowire Growth with Binary Metal Alloys

“…The behavior of the triple phase boundary (TPB) at the nanowire-liquid metal interface provides an understanding of growth phenomenon at an atomic level [11][12][13][14][15]. For example, interfacial energies and capillary forces during steady-state nanowire growth determine the dynamics of the seed droplet at the tip of a nanowire [12,16].…”