title: High-resolution detection of Au catalyst atoms in Si nanowires.
abstract: The potential for the metal nanocatalyst to contaminate vapour-liquid-solid grown semiconductor nanowires has been a long-standing concern, because the most common catalyst material, Au, is highly detrimental to the performance of minority carrier electronic devices. We have detected single Au atoms in Si nanowires grown using Au nanocatalyst particles in a vapour-liquid-solid process. Using high-angle annular dark-field scanning transmission electron microscopy, Au atoms were observed in higher numbers than expected from a simple extrapolation of the bulk solubility to the low growth temperature. Direct measurements of the minority carrier diffusion length versus nanowire diameter, however, demonstrate that surface recombination controls minority carrier transport in as-grown n-type nanowires; the influence of Au is negligible. These results advance the quantitative correlation of atomic-scale structure with the properties of nanomaterials and can provide essential guidance to the development of nanowire-based device technologies.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Allen
authors.forename: Eric R
authors.initials: ER
authors.lastname: Hemesath
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Perea
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Lensch-Falk
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Yin
authors.forename: Mhairi H
authors.initials: MH
authors.lastname: Gass
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Bleloch
authors.forename: Richard E
authors.initials: RE
authors.lastname: Palmer
authors.forename: Lincoln J
authors.initials: LJ
authors.lastname: Lauhon
mesh_terms: D006046:Gold / Q000032:analysis*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D017348:Microscopy, Electron, Scanning Transmission / Q000379:methods*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012825:Silicon / Q000032:analysis*
chemical_list: D006046:Gold; D012825:Silicon