title: Surface effects of vapour-liquid-solid driven Bi surface droplets formed during molecular-beam-epitaxy of GaAsBi.
abstract: Herein we investigate a (001)-oriented GaAs1-xBix/GaAs structure possessing Bi surface droplets capable of catalysing the formation of nanostructures during Bi-rich growth, through the vapour-liquid-solid mechanism. Specifically, self-aligned "nanotracks" are found to exist trailing the Bi droplets on the sample surface. Through cross-sectional high-resolution transmission electron microscopy the nanotracks are revealed to in fact be elevated above surface by the formation of a subsurface planar nanowire, a structure initiated mid-way through the molecular-beam-epitaxy growth and embedded into the epilayer, via epitaxial overgrowth. Electron microscopy studies also yield the morphological, structural, and chemical properties of the nanostructures. Through a combination of Bi determination methods the compositional profile of the film is shown to be graded and inhomogeneous. Furthermore, the coherent and pure zincblende phase property of the film is detailed. Optical characterisation of features on the sample surface is carried out using polarised micro-Raman and micro-photoluminescence spectroscopies. The important light producing properties of the surface nanostructures are investigated through pump intensity-dependent micro-PL measurements, whereby relatively large local inhomogeneities are revealed to exist on the epitaxial surface for important optical parameters. We conclude that such surface effects must be considered when designing and fabricating optical devices based on GaAsBi alloys.
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: J A
authors.initials: JA
authors.lastname: Steele
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: R A
authors.initials: RA
authors.lastname: Lewis
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Horvat
authors.affiliation: Electron Microscopy Centre, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: M J B
authors.initials: MJ
authors.lastname: Nancarrow
authors.affiliation: School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Center, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Henini
authors.affiliation: Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.|Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: D
authors.initials: D
authors.lastname: Fan
authors.affiliation: Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Y I
authors.initials: YI
authors.lastname: Mazur
authors.affiliation: Leibniz-Institute for Crystal Growth, Max-Born-Str. 2, D-12489 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmidbauer
authors.affiliation: Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.|Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Ware
authors.affiliation: Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.|Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: S-Q
authors.initials: SQ
authors.lastname: Yu
authors.affiliation: Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: G J
authors.initials: GJ
authors.lastname: Salamo