Microstructurally Correlated Flexural Nanomechanics of Single Nanowires Using an On-Chip Platform

This article presents a new on-chip platform for combining atomic force microscopy (AFM) based flexural nanomechanics with ex-situ transmission electron microscopy (TEM) based microstructural investigation of single nanowire beams. The on-chip platform facilitates the dielectrophoretic assembly of a single nanowire (NW) into a doubly-clamped nanobeam on a pre-fabricated membrane, which contains a through-hole as an electron-transparent viewing window for TEM imaging. Contact-mode AFM is employed to perform loading-unloading experiments on the NW with a concomitant acquisition of force vs. displacement plots and device topographical scans. TEM imaging delivers complementary data involving NW dimensions, loading orientation with respect to the material crystallographic directions, and pre- / post-mechanics imaging as well as electron diffraction patterns. Moreover, a finite-element model is utilized to extract material mechanical parameters such as Young's modulus and fracture strength from the experimental data sets. Through the use of battery-relevant, tunnel-structured Na_0.17MnO₂ NWs as the model material system, this new capability delivers the following contributions: i) obtaining flexural nanomechanics induced force vs deflection data, ii) direct microstructural investigation of the pre- and post-mechanics sample, and iii) a methodology to quantify the impact of NW contamination during the electron-beam induced deposition (EBID) based clamping metal process, which is commonly used in the sample preparation steps of similar doubly-clamped nanobeams, and to thereby, accurately determine the intrinsic mechanical properties of the NW material system.