title: Catalyst composition and impurity-dependent kinetics of nanowire heteroepitaxy.
abstract: The mechanisms and kinetics of axial Ge-Si nanowire heteroepitaxial growth based on the tailoring of the Au catalyst composition via Ga alloying are studied by environmental transmission electron microscopy combined with systematic ex situ CVD calibrations. The morphology of the Ge-Si heterojunction, in particular, the extent of a local, asymmetric increase in nanowire diameter, is found to depend on the Ga composition of the catalyst, on the TMGa precursor exposure temperature, and on the presence of dopants. To rationalize the findings, a general nucleation-based model for nanowire heteroepitaxy is established which is anticipated to be relevant to a wide range of material systems and device-enabling heterostructures.
authors.affiliation: Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Gamalski
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Perea
authors.forename: Jinkyoung
authors.initials: J
authors.lastname: Yoo
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Olszta
authors.forename: Robert
authors.initials: R
authors.lastname: Colby
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Schreiber
authors.forename: Caterina
authors.initials: C
authors.lastname: Ducati
authors.forename: S Tom
authors.initials: ST
authors.lastname: Picraux
authors.forename: Stephan
authors.initials: S
authors.lastname: Hofmann