Micromachined silicon grids for direct TEM and Raman characterization of CVD grown carbon nanotubes

摘要

Transmission electron microscopy (TEM) and micro-Raman spectroscopy are key techniques in the structural characterization of carbon nanotubes. For device applications, carbon nanotubes are typically grown by chemical vapor deposition (CVD) on silicon substrates. However, TEM requires very thin samples, which are electron transparent. Therefore, for TEM analysis, CVD grown nanotubes are typically deposited on commercial TEM grids by postprocessing. This procedure has two problems: It can damage the nanotubes, and it does not work reliably if the nanotube density is too low. The ability to do TEM directly on as-grown nanotubes lying on the silicon substrate would solve these two problems. In this talk, for this purpose, we fabricate micromachined TEM grids from silicon substrates. Subsequently, we grow nanotubes on these micromachined TEM grids by CVD, and characterize the nanotubes by TEM, micro-Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). We show that these substrates provide a low cost, mass producible, efficient, and reliable platform for direct TEM, Raman, AFM, and SEM analysis of as-grown nanotubes or other nanomaterials on the same substrate, eliminating the need for any postprocessing after CVD growth.