tailieunhanh - Báo cáo hóa học: " Fabrication of Coaxial Si12xGex Heterostructure Nanowires by O2 Flow-Induced Bifurcate Reactions"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Fabrication of Coaxial Si12xGex Heterostructure Nanowires by O2 Flow-Induced Bifurcate Reactions | Nanoscale Res Lett 2010 5 1535-1539 DOI s11671-010-9673-3 NANO EXPRESS Fabrication of Coaxial Sii-xGex Heterostructure Nanowires by O2 Flow-Induced Bifurcate Reactions Ilsoo Kim Ki-Young Lee Ungkil Kim Yong-Hee Park Tae-Eon Park Heon-Jin Choi Received 21 April 2010 Accepted 7 June 2010 Published online 17 June 2010 The Author s 2010. This article is published with open access at Abstract We report on bifurcate reactions on the surface of well-aligned Si1-xGex nanowires that enable fabrication of two different coaxial heterostructure nanowires. The Si1-xGex 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 Si1-xGex or SiO2 Si1-xGex coaxial heterostructure nanowires. The rate of deposition and oxidation was dominated by interfacial reaction and diffusion of oxygen through the oxide layer respectively. Keywords Si1-xGex nanowires Coaxial heterostructure Bifurcate reactions Interfacial reaction Diffusion-controlled reaction Self-limiting oxidation Kinetics of gas diffusion heterostructures in the nanowires should enable diverse functions that are promising for high-performance nanowire devices 2-4 . Indeed recent studies of heterostructure semiconductor nanowires for electronics such as diodes 3 field-effect transistors FETs 5 sensors 6 and the solar cell 7 have demonstrated the higher performances that are ascribed to heterostructures. Fabrication of heterostructure nanowires have been mostly carried out by consecutive chemical vapor deposition which supplies precursors one by one in the order of layer stacking sequences 8 9