The team from Peking University, China, used a CEB in a high-resolution TEM (Tecnai F30, 300 kV) to reshape the structures. Circular nanopores were drilled in a few minutes when a high-energy electron beam was converged to a bright spot on free-standing Si3N4 membranes. By moving the CEB to an area near one corner of the nanopore, deformation with the desired geometry could be realized directly.

Painting with electrons

To achieve the anticipated pattern or structure, the irradiation spot of the electron beam can be moved at will, using it as a "paintbrush", starting from an initial nanopore and stopping when the desired geometry is obtained. Different geometries can be fabricated with the same nanopore sequentially.

Nanoslits with a 2 or 3 nm width and 100 nm length were realized by this approach (see image above), which can find applications as supporting membranes and masks. The geometry of nanostructures can be modified under irradiation of the electron beam to a lower surface free energy in the fluid state, with the help of the knock-on effect from the CEB.

The group's results provide a new perspective for nanopore-based device fabrication, which would open up more substantial opportunities for nanoelectronics and nanofuidics.

Additional details can be found in the journal Nanotechnology.