In situ Control of Atomic-Scale Si Layer with Huge Strain in the Nanoheterostructure NiSi/Si/NiSi through Point Contact Reaction

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• 作者：Kuo-Chang Lu ; Wen-Wei Wu ; Han-Wei Wu ; Carey M. Tanner ; Jane P. Chang ; Lih J. Chen ; K. N. Tu
• 刊名：Nano Letters
• 出版年：2007
• 出版时间：August 2007
• 年：2007
• 卷：7
• 期：8
• 页码：2389 - 2394
• 全文大小：581K
• 年卷期：v.7,no.8(August 2007)
• ISSN：1530-6992

文摘

Nanoheterostructures of NiSi/Si/NiSi in which the length of the Si region can be controlled down to 2 nm have been produced using in situpoint contact reaction between Si and Ni nanowires in an ultrahigh vacuum transmission electron microscope. The Si region was found to behighly strained (more than 12%). The strain increases with the decreasing Si layer thickness and can be controlled by varying the heatingtemperature. It was observed that the Si nanowire is transformed into a bamboo-type grain of single-crystal NiSi from both ends following thepath with low-activation energy. We propose the reaction is assisted by interstitial diffusion of Ni atoms within the Si nanowire and is limitedby the rate of dissolution of Ni into Si at the point contact interface. The rate of incorporation of Ni atoms to support the growth of NiSi hasbeen measured to be 7 × 10^-4 s per Ni atom. The nanoscale epitaxial growth rate of single-crystal NiSi has been measured using high-resolution lattice-imaging videos. On the basis of the rate, we can control the consumption of Si and, in turn, the dimensions of thenanoheterostructure down to less than 2 nm, thereby far exceeding the limit of conventional patterning process. The controlled huge strainin the controlled atomic scale Si region, potential gate of Si nanowire-based transistors, is expected to significantly impact the performanceof electronic devices.