Fabrication and characterization of the metal nanosized branched structures and the composite nanostructures grown on insulator substrates by the EBID process

Using an electron-beam-induced deposition (EBID) process in a transmission electron microscope, we fabricated self-standing metal nanosized branched structures including nanowire arrays, nanodendrites, and nanofractal-like trees, as well as their composite nanostructures with controlled size and position on insulator (SiO₂, Al₂O₃) substrates. The fabricated nanostructures were characterized with high-resolution transmission electron microscopy and X-ray energy dispersive spectroscopy. The growth mechanism was discussed. Effect of the electron-beam accelerating voltage on crystallization of the nanostructures was investigated. The nanostructures of the different morphologies were obtained by controlling the intensity of the electron beam during the EBID process. A mechanism for the growth and morphology of the nanostructures was proposed involving charge-up produced on the surface of the substrate, and the movement of the charges to and charges accumulation at the convex surface of the substrate and the tips of the deposits. High-energy electron irradiation enhanced diffusion of the metallic atoms in the nanostructures and hence promoted crystallization. More crystallized metal nanobranched structures were achieved by the EBID process using high energy electron beams.