Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore.
ACS Nano. 2010 May 25;4(5):2901-9. doi: 10.1021/nn1000996.
We report the fabrication of micro/nanoscale pits with facile shape, orientation, and size controls on an Si surface via an Au-nanoparticles-assisted vapor transport method. The pit dimensions can be continuously tuned from 70 nm to several mum, and the shapes of triangles, squares, and wire/hexagons are prepared on Si (111), (100), and (110) substrates, respectively. This reliable shape control hinges on the anisotropic diffusivity of Co in Si and the sublimation of cobalt silicide nanoislands. The experimental conditions, in particular the substrate orientation and the growth temperature, dictate the pit morphology. On the basis of this understanding of the mechanism and the morphological evolution of the pits, we manage to estimate the diffusion coefficients of Co in bulk Si along the 100 and 111 directions, that is D(100) and D(111). These diffusion coefficients show strong temperature dependence, for example, D(100) is ca. 3 times larger than D(111) at 860 degrees C, while they approach almost the same value at 1000 degrees C. This simple bottom-up route may help to develop new technologies for Si-based nanofabrication and to find potential applications in constructing nanodevices.
我们报告了一种在 Si 表面上通过 Au 纳米粒子辅助气相传输方法制造具有简便形状、取向和尺寸控制的微/纳米级凹坑的方法。凹坑尺寸可以从 70nm 连续调谐到几微米，并且三角形、正方形和线/六边形的形状分别在 Si（111）、（100）和（110）衬底上制备。这种可靠的形状控制取决于 Co 在 Si 中的各向异性扩散和钴硅化物纳米岛的升华。实验条件，特别是衬底取向和生长温度，决定了凹坑的形态。基于对机制和凹坑形态演化的理解，我们设法估计了 Co 在体 Si 中沿 100 和 111 方向的扩散系数，即 D（100）和 D（111）。这些扩散系数表现出强烈的温度依赖性，例如，在 860°C 时 D（100）约为 D（111）的 3 倍，而在 1000°C 时它们几乎接近相同的值。这种简单的自下而上的方法可能有助于开发基于 Si 的纳米制造新技术，并找到在构建纳米器件中的潜在应用。
