title: Record pure zincblende phase in GaAs nanowires down to 5 nm in radius.
abstract: We report the Au catalyst-assisted synthesis of 20 μm long GaAs nanowires by the vapor-liquid-solid hydride vapor phase epitaxy (HVPE) exhibiting a polytypism-free zincblende phase for record radii lower than 15 nm down to 5 nm. HVPE makes use of GaCl gaseous growth precursors at high mass input of which fast dechlorination at the usual process temperature of 715 °C results in high planar growth rate (standard 30-40 μm/h). When it comes to the vapor-liquid-solid growth of nanowires, fast solidification at a rate higher than 100 μm/h is observed. Nanowire growth by HVPE only proceeds by introduction of precursors in the catalyst droplets from the vapor phase. This promotes almost pure axial growth leading to nanowires with a constant cylinder shape over unusual length. The question of the cubic zincblende structure observed in HVPE-grown GaAs nanowires regardless of their radius is at the heart of the paper. We demonstrate that the vapor-liquid-solid growth in our conditions takes place at high liquid chemical potential that originates from very high influxes of both As and Ga. This yields a Ga concentration systematically higher than 0.62 in the Au-Ga-As droplets. The high Ga concentration decreases the surface energy of the droplets, which disables nucleation at the triple phase line thus preventing the formation of wurtzite structure whatever the nanowire radius is.
authors.affiliation: Clermont Université, Université Blaise Pascal , Institut Pascal, BP 10448, F-63000 Clermont-Ferrand, France.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Gil
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Dubrovskii
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Avit
authors.forename: Yamina
authors.initials: Y
authors.lastname: André
authors.forename: Christine
authors.initials: C
authors.lastname: Leroux
authors.forename: Kaddour
authors.initials: K
authors.lastname: Lekhal
authors.forename: Jurij
authors.initials: J
authors.lastname: Grecenkov
authors.forename: Agnès
authors.initials: A
authors.lastname: Trassoudaine
authors.forename: Dominique
authors.initials: D
authors.lastname: Castelluci
authors.forename: Guillaume
authors.initials: G
authors.lastname: Monier
authors.forename: Reda M
authors.initials: RM
authors.lastname: Ramdani
authors.forename: Christine
authors.initials: C
authors.lastname: Robert-Goumet
authors.forename: Luc
authors.initials: L
authors.lastname: Bideux
authors.forename: Jean Christophe
authors.initials: JC
authors.lastname: Harmand
authors.forename: Frank
authors.initials: F
authors.lastname: Glas