Synthesis of crystalline metal nanomonoliths by e-beam reduction of negatively electrified jets

Abstract

Direct writing of nanoscale structures with focused electron beam–induced deposition (FEBID) is a promising route to atom-by-atom growth of complex three-dimensional nanostructures, but application has been constrained by slow growth rates (largely due to low precursor density), a limited selection of non-carbonaceous precursors, and a highly carbonaceous material composition resulting from the dissociative decomposition growth mechanism and organometallic precursors used in gas-phase FEBID. In this article, we report on the discovery of a new mode for liquid phase FEBID that enables growth of large metallic crystalline monoliths at exceptionally high growth rates (>1 μm3/s) from water-dissolved metal salts using nanoelectrospray-induced non-equilibrium electrochemistry. Deposit morphology is controlled using the bias of the electrospray, with negative electrospray promoting crystallinity (as opposed to positive electrospray which results in granular deposits). Crystallinity is further promoted by elevating the pH of the electrospray solution. This approach opens a pathway for rapid direct writing of larger-scale monolithic metal structures using an electron beam.