Writing Silica Structures in Liquid with Scanning Transmission Electron Microscopy

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2015-02, Vol.11 (5), p.585-590
• Main Authors: van de Put, Marcel W. P., Carcouët, Camille C. M. C., Bomans, Paul H. H., Friedrich, Heiner, de Jonge, Niels, Sommerdijk, Nico A. J. M.
• Format: Article
• Language: English
• Subjects: atomic force microscopy; Deposition; Electrolytic cells; liquid cells; Liquids; Membranes; Nanoparticles; Nanotechnology; patterning; Scanning electron microscopy; Scanning transmission electron microscopy; silica nanoparticles; Silicon dioxide; STEM; Transmission electron microscopy
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201400913

Silica nanoparticles are imaged in solution with scanning transmission electron microscopy (STEM) using a liquid cell with silicon nitride (SiN) membrane windows. The STEM images reveal that silica structures are deposited in well‐defined patches on the upper SiN membranes upon electron beam irradiation. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm‐diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub‐micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. A solution containing silica nanoparticles is confined in a liquid cell, between two electron transparent silicon nitride membranes. In STEM imaging, the focused electron beam creates a locally increased pH through the electrolysis of water, which is used for the controlled deposition of merged silica nanoparticles. This process offers new possibilities for creating 3D structures in liquid.