Question

Write a paragraph to show how to apply TEM techniques in nanowire research?

Answer 1

Nanowires show great promise for development in many technological applications including electronics, photonics, and displays . Due to the fine scale of nanowires, transmission electron microscopy (TEM) and atom probe tomography (APT) are among a limited number of techniques that can measure the crystallographic and chemical nature of these structures which ultimately define their performance. Performing TEM analysis of the sample before atom probe analysis is useful not only for obtaining complementary information about the crystal structure(s), but also for assisting in accuracy of the reconstruction. The radius, shank angle, layer thicknesses, and other structural information can be directly measured and incorporated into the atom probe reconstruction. This work expands the previously reported technique to both dispersed and substrate grown nanowires. This technique as applied to nanowires utilizes only the electron beam in order to avoid structural damage from the FIB column. In the first adaptation, the nanowires were removed from their substrate, suspended in ethanol, and then dispersed over a porous substrate. This geometry allows most of the nanowires to be retained on the surface suspended over the pore openings . A nano-manipulator was placed in close proximity to the nanowire’s base. A very small electron beam deposited platinum (e-beam Pt) weld was made at that location to provide just enough attachment to remove the wire from the porous substrate The nanowire was then moved to a TEM grid that had been sectioned such that a vertical portion of each grid bar extended beyond the horizontal grid bar. The nanowire was aligned with a vertical grid bar and securely welded with e-beam Pt. The nano-manipulator was then slowly drawn away from the nanowire until the initial small weld detached, leaving the nanowire mounted to the TEM half-grid