Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan.
Nano Lett. 2010 Oct 13;10(10):3984-9. doi: 10.1021/nl101842w.
Forming functional circuit components in future nanotechnology requires systematic studies of solid-state chemical reactions in the nanoscale. Here, we report efficient and unique methods, point and line contact reactions on Si nanowires, fabricating high quality and quantity of multiple nanoheterostructures of NiSi/Si and investigation of NiSi formation in nanoscale. By using the point contact reaction between several Ni nanodots and a Si nanowire carried out in situ in an ultrahigh vacuum transmission electron microscopy, multiple sections of single-crystal NiSi and Si with very sharp interfaces were produced in a Si nanowire. Owing to the supply limited point contact reaction, we propose that the nucleation and growth of the sugar cane-type NiSi grains start at the middle of the point contacts between two Ni nanodots and a Si nanowire. The reaction happens by the dissolution of Ni into the Si nanowire at the point contacts and by interstitial diffusion of Ni atoms within a Si nanowire. The growth of NiSi stops as the amount of Ni in the Ni nanodots is consumed. Additionally, without lithography, utilizing the line contact reaction between PS nanosphere-mediated Ni nanopatterns and a nanowire of Si, we have fabricated periodic multi-NiSi/Si/NiSi heterostructure nanonowires that may enhance the development of circuit elements in nanoscale electronic devices. Unlike the point contact reaction, silicide growth starts at the contact area in the line contact reaction; the different silicide formation modes resulting from point and line contact reactions are compared and analyzed. A mechanism on the basis of flux divergence is proposed for controlling the growth of the nano-multiheterostructures.
在未来的纳米技术中形成功能性电路组件需要对固态化学反应进行系统研究。在这里，我们报告了在 Si 纳米线中进行高效且独特的点和线接触反应的方法，用于制造大量高质量的 NiSi/Si 纳米异质结构，并研究了纳米尺度下的 NiSi 形成。通过在超高真空透射电子显微镜中进行原位实验，利用几个 Ni 纳米点与 Si 纳米线之间的点接触反应，在 Si 纳米线中产生了多个单晶 NiSi 和 Si 的部分，具有非常尖锐的界面。由于点接触反应的供应有限，我们提出了在两个 Ni 纳米点与 Si 纳米线之间的点接触处开始形成糖棒型 NiSi 晶粒的成核和生长。反应通过 Ni 在点接触处溶解到 Si 纳米线中以及 Ni 原子在 Si 纳米线中的间隙扩散来发生。随着 Ni 纳米点中 Ni 的量被消耗，NiSi 的生长停止。此外，我们还通过无光刻技术，利用 PS 纳米球介导的 Ni 纳米图案与 Si 纳米线之间的线接触反应，制造了周期性的多 NiSi/Si/NiSi 异质结构纳米线，这可能会促进纳米尺度电子设备中电路元件的发展。与点接触反应不同，在线接触反应中，硅化物的生长始于接触区域；比较和分析了点接触和线接触反应产生的不同硅化物形成模式。提出了一种基于通量发散的机制来控制纳米多异质结构的生长。
