title: Silicon-in-silica spheres via axial thermal gradient in-fibre capillary instabilities.
abstract: The ability to produce small scale, crystalline silicon spheres is of significant technological and scientific importance, yet scalable methods for doing so have remained elusive. Here we demonstrate a silicon nanosphere fabrication process based on an optical fibre drawing technique. A silica-cladded silicon-core fibre with diameters down to 340 nm is continuously fed into a flame defining an axial thermal gradient and the continuous formation of spheres whose size is controlled by the feed speed is demonstrated. In particular, spheres of diameter <500 nm smaller than those produced under isothermal heating conditions are shown and analysed. A fibre with dual cores, p-type and n-type silicon, is drawn and processed into spheres. Spatially coherent break-up leads to the joining of the spheres into a bispherical silicon 'p-n molecule'. The resulting device is measured to reveal a rectifying I-V curve consistent with the formation of a p-n junction.
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Gumennik
authors.forename: Lei
authors.initials: L
authors.lastname: Wei
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lestoquoy
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Stolyarov
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Jia
authors.forename: Paul H
authors.initials: PH
authors.lastname: Rekemeyer
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Smith
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Liang
authors.forename: Benjamin J-B
authors.initials: BJ
authors.lastname: Grena
authors.forename: Steven G
authors.initials: SG
authors.lastname: Johnson
authors.forename: Silvija
authors.initials: S
authors.lastname: Gradečak
authors.forename: Ayman F
authors.initials: AF
authors.lastname: Abouraddy
authors.forename: John D
authors.initials: JD
authors.lastname: Joannopoulos
authors.forename: Yoel
authors.initials: Y
authors.lastname: Fink