title: Fabrication of Coaxial Si(1-x)Ge(x) Heterostructure Nanowires by O(2) Flow-Induced Bifurcate Reactions.
abstract: We report on bifurcate reactions on the surface of well-aligned Si(1-x)Ge(x) nanowires that enable fabrication of two different coaxial heterostructure nanowires. The Si(1-x)Ge(x) nanowires were grown in a chemical vapor transport process using SiCl(4) gas and Ge powder as a source. After the growth of nanowires, SiCl(4) flow was terminated while O(2) gas flow was introduced under vacuum. On the surface of nanowires was deposited Ge by the vapor from the Ge powder or oxidized into SiO(2) by the O(2) gas. The transition from deposition to oxidation occurred abruptly at 2 torr of O(2) pressure without any intermediate region and enables selectively fabricated Ge/Si(1-x)Ge(x) or SiO(2)/Si(1-x)Ge(x) coaxial heterostructure nanowires. The rate of deposition and oxidation was dominated by interfacial reaction and diffusion of oxygen through the oxide layer, respectively.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Korea.
authors.forename: Ilsoo
authors.initials: I
authors.lastname: Kim
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Lee
authors.forename: Ungkil
authors.initials: U
authors.lastname: Kim
authors.forename: Yong-Hee
authors.initials: YH
authors.lastname: Park
authors.forename: Tae-Eon
authors.initials: TE
authors.lastname: Park
authors.forename: Heon-Jin
authors.initials: HJ
authors.lastname: Choi