title: Interaction between lamellar twinning and catalyst dynamics in spontaneous core-shell InGaP nanowires.
abstract: Semiconductor nanowires oriented along the [211] direction usually present twins parallel to their axis. For group IV nanowires this kind of twin allows the formation of a catalyst-nanowire interface composed of two equivalent {111} facets. For III-V nanowires, however, the twin will generate two facets with different polarities. In order to keep the <211> orientation stable, a balance in growth rates for these different facets must be reached. We report here the observation of stable, micron-long <211>-oriented InGaP nanowires with a spontaneous core-shell structure. We show that stacking fault formation in the crystal region corresponding to the {111}A facet termination provides a stable NW/NP interface for growth along the <211> direction. During sample cool down, however, the catalyst migrates to a lateral {111}B facet, allowing the growth of branches perpendicular to the initial orientation. In addition to that, we show that the core-shell structure is non-concentric, most likely due to the asymmetry between the facets formed in the NW sidewall; this effect generates stress along the nanowire, which can be relieved through bending.
authors.affiliation: Instituto de Física "GlebWataghin", Universidade Estadual de Campinas, UNICAMP, 13083-859, Campinas, SP, Brazil. doug@ifi.unicamp.br.
authors.forename: D S
authors.initials: DS
authors.lastname: Oliveira
authors.forename: L H G
authors.initials: LH
authors.lastname: Tizei
authors.forename: A
authors.initials: A
authors.lastname: Li
authors.forename: T L
authors.initials: TL
authors.lastname: Vasconcelos
authors.forename: C A
authors.initials: CA
authors.lastname: Senna
authors.forename: B S
authors.initials: BS
authors.lastname: Archanjo
authors.forename: D
authors.initials: D
authors.lastname: Ugarte
authors.forename: M A
authors.initials: MA
authors.lastname: Cotta