Fabrication of Coaxial Si_{1&#8722;<it>x</it>}Ge_<it>x</it> Heterostructure Nanowires by O₂ Flow-Induced Bifurcate Reactions

• Main Authors: Kim Ilsoo, Lee Ki-Young, Kim Ungkil, Park Yong-Hee, Park Tae-Eon, Choi Heon-Jin
• Format: Article
• Language: English
• Published: SpringerOpen 2010-01-01
• Series: Nanoscale Research Letters
• Subjects: Si_{1&#8722;<it>x</it>}Ge_<it>x</it> nanowires; Coaxial heterostructure; Bifurcate reactions; Interfacial reaction; Diffusion-controlled reaction; Self-limiting oxidation; Kinetics of gas diffusion
• Online Access: http://dx.doi.org/10.1007/s11671-010-9673-3

<p>Abstract</p> <p>We report on bifurcate reactions on the surface of well-aligned Si_{1&#8722;<it>x</it>}Ge_<it>x</it> nanowires that enable fabrication of two different coaxial heterostructure nanowires. The Si_{1&#8722;<it>x</it>}Ge_<it>x</it> nanowires were grown in a chemical vapor transport process using SiCl₄ gas and Ge powder as a source. After the growth of nanowires, SiCl₄ flow was terminated while O₂ gas flow was introduced under vacuum. On the surface of nanowires was deposited Ge by the vapor from the Ge powder or oxidized into SiO₂ by the O₂ gas. The transition from deposition to oxidation occurred abruptly at 2 torr of O₂ pressure without any intermediate region and enables selectively fabricated Ge/Si_{1&#8722;<it>x</it>}Ge_<it>x</it> or SiO₂/Si_{1&#8722;<it>x</it>}Ge_<it>x</it> coaxial heterostructure nanowires. The rate of deposition and oxidation was dominated by interfacial reaction and diffusion of oxygen through the oxide layer, respectively.</p>