title: 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.
authors.affiliation: Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK. sh315@cam.ac.uk
authors.forename: Stephan
authors.initials: S
authors.lastname: Hofmann
authors.forename: Renu
authors.initials: R
authors.lastname: Sharma
authors.forename: Christoph T
authors.initials: CT
authors.lastname: Wirth
authors.forename: Felipe
authors.initials: F
authors.lastname: Cervantes-Sodi
authors.forename: Caterina
authors.initials: C
authors.lastname: Ducati
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski
authors.forename: Jeff
authors.initials: J
authors.lastname: Drucker
authors.forename: Peter
authors.initials: P
authors.lastname: Bennett
authors.forename: John
authors.initials: J
authors.lastname: Robertson