Conductive cobalt-based deposits grown by Cryo-FEBID for application as top-contact electrodes in large-area molecular electronic devices.

The growth of functional materials at precise locations using focused electron irradiation has recently attracted considerable attention, including techniques such as Focused Electron Beam Induced Deposition (FEBID), growth by decomposition of spin-coated organometallic films, ice lithography, and others. Ice lithography requires lowering the substrate temperature, which can be achieved by means of a cryogenic module or a Peltier accessory. The same approach is applied to FEBID growth under cryogenic conditions (Cryo-FEBID) and to the related technique Cryo-FIBID, where ions constitute the irradiating charge instead of electrons. These techniques outperform their corresponding room-temperature processes due to their higher speed. In this manuscript, we present the optimization of cobalt-based deposit growth using Cryo-FEBID. For the first time, a conductive material grown using Cryo-FEBID is demonstrated, opening the possibility of applying this technique to create nanoscale electrical contacts. These cobalt-based Cryo-FEBID deposits are used to fabricate the top-contact electrode in vertical, large-area molecular electronic devices, achieving state-of-the-art yield and performance. Importantly, this nanofabrication method offers unique advantages, including direct-writing with precise control over substrate location, size, shape and thickness, paving the way for the integration of molecular-scale functionalities into conventional microelectronic platforms.