title: Plasma-Assisted Growth of Silicon Nanowires by Sn Catalyst: Step-by-Step Observation.
abstract: A comprehensive study of the silicon nanowire growth process has been carried out. Silicon nanowires were grown by plasma-assisted-vapor-solid method using tin as a catalyst. We have focused on the evolution of the silicon nanowire density, morphology, and crystallinity. For the first time, the initial growth stage, which determines the nanowire (NW) density and growth direction, has been observed step by step. We provide direct evidence of the merging of Sn catalyst droplets and the formation of Si nanowires during the first 10 s of growth. We found that the density of Sn droplets decreases from ~9000 Sn droplets/μm2to 2000 droplets/μm2after just 10 s of growth. Moreover, the long and straight nanowire density decreases from 170/μm2after 2 min of growth to less than 10/μm2after 90 min. This strong reduction in nanowire density is accompanied by an evolution of their morphology from cylindrical to conical, then to bend conical, and finally, to a bend inverted conical shape. Moreover, the changes in the crystalline structure of nanowires are from (i) monocrystalline to (ii) monocrystalline core/defective crystalline shell and then to (iii) monocrystalline core/defective crystalline shell/amorphous shell. The evolutions of NW properties have been explained in detail.
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Jian
authors.initials: J
authors.lastname: Tang
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Maurice
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Wanghua
authors.initials: W
authors.lastname: Chen
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Soumyadeep
authors.initials: S
authors.lastname: Misra
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Foldyna
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France.
authors.forename: Erik V
authors.initials: EV
authors.lastname: Johnson
authors.affiliation: LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128, Palaiseau, France. pere.roca@polytechnique.edu.
authors.forename: Pere
authors.initials: P
authors.lastname: Roca I Cabarrocas
keywords: Growth process; PECVD; Silicon nanowires; Sn; VLS