Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2 V4.
Langmuir. 2010 Nov 16;26(22):17558-67. doi: 10.1021/la103070x. Epub 2010 Sep 29.
The high surface area, large aspect ratio, and porous nature of nanorod arrays make them excellent foundation materials for many devices. Of the many synthesis techniques for forming nanorods, glancing angle deposition (GLAD) offers one of the more straightforward and flexible methods for ensuring control of alignment, porosity, and architecture of the nanorods. Here we demonstrate the first use of a dual-beam (focused ion beam (FIB) combined with scanning electron microscopy (SEM)) instrument to section and image the internal morphology of a nanorod array fabricated using the GLAD technique. We have used the FIB-SEM to reconstruct the 3D composition of TiO(2) nanorods, allowing us to visualize for the first time the core structures of many potential devices. We have also been able to probe the relationship between critical parameters such as diameter (w(act)), internanorod spacing (ν(act)), center-to-center spacing (c(act)), and nanorod population density (d(act)) and the depth of the nanocolumn (t) for a single homogeneous structure. A continuous data set was obtained from a single 5-μm-thick GLAD film, avoiding the artifacts arising from the analysis of the top surfaces of multiple samples of varying thicknesses. An analysis of the acquired sectioned data has allowed us to determine that the critical nanocolumn parameters follow a power-law scaling trend with w(act) = 9.4t(0.35) nm, ν(act) = 15.2t(0.25) nm, c(act) = 24.8t(0.31) nm, and d(act) = 3402t(-0.65) columns μm(-2). Using the FIB/SEM images acquired for the TiO(2) nanorods, we have also investigated the evolution of individual nanocolumns and have observed that bifurcation and branching play a significant role in the extinction or survival of these nanorods. These findings will allow for the optimization of nanorod properties for device applications. Also, the FIB sectioning and reconstruction process developed here will permit for the investigation of nanorod arrays formed from a range of synthesis techniques and materials.
纳米棒阵列具有高的比表面积、大的纵横比和多孔的性质，使它们成为许多设备的极好的基础材料。在形成纳米棒的许多合成技术中，掠角沉积（GLAD）提供了一种更简单、更灵活的方法，可以确保纳米棒的对齐、多孔性和结构的控制。在这里，我们展示了首次使用双束（聚焦离子束（FIB）与扫描电子显微镜（SEM）结合）仪器来对使用 GLAD 技术制造的纳米棒阵列进行切片和成像，以分析其内部形态。我们已经使用 FIB-SEM 重建了 TiO2 纳米棒的 3D 组成，使我们能够首次可视化许多潜在设备的核心结构。我们还能够探测直径（w（act））、纳米棒间间隔（ν（act））、中心到中心间隔（c（act））和纳米棒种群密度（d（act））等关键参数与单个同质结构的纳米柱深度（t）之间的关系。从单个 5μm 厚的 GLAD 薄膜中获得了连续数据集，避免了分析不同厚度的多个样品的顶表面而产生的伪影。对所获取的切片数据的分析使我们能够确定关键纳米柱参数遵循幂律缩放趋势，其中 w（act）= 9.4t（0.35）nm，ν（act）= 15.2t（0.25）nm，c（act）= 24.8t（0.31）nm，d（act）= 3402t（-0.65）个柱μm（-2）。使用针对 TiO2 纳米棒获得的 FIB/SEM 图像，我们还研究了单个纳米柱的演化，并观察到分叉和分支在这些纳米棒的消失或存活中起着重要作用。这些发现将允许优化纳米棒的性质以用于器件应用。此外，这里开发的 FIB 切片和重建过程将允许对使用各种合成技术和材料形成的纳米棒阵列进行研究。
