Nanoscale cold welding of glass

Bottom-up assembly and joining of silica nanoparticles to form complicated geometries up to three-dimensional (3D) glass structures are attractive for nanoscale optical, optoelectronics, etc. Most existing silica 3D printing techniques can only achieve submicron-level precision due to the optical limit of vat photopolymerization, which presents critical challenges for sub-100 nm printing. In this context, we introduce an electron-beam-assisted cold welding technique for nanoscale glass that is capable of achieving precision at the tens-of-nanometers scale. This method enables the direct fusion of two amorphous silica nanospheres within a few seconds while keeping the diameter smaller than 100 nm. Meanwhile, the strength, composition, and structure of the as-welded junctions appear the same as those of the pristine silica. Our approach would potentially allow ultra-high-resolution 3D bottom-up assembly and printing of silica nanostructures with ultimate resolution subject to the nanoparticle size only, which offers a new approach for additive manufacturing of nanoscale glass devices.