Electrical gating based on ion and electron beam irradiation of PdAc films: Application to superconducting nanowires

Focused ion beam (FIB) is a nanopatterning technique commonly used for material removal, but in combination with a precursor material it gives rise to additive nanomanufacturing, of great interest in nanotechnology and semiconductor applications. The precursor material can be delivered onto the substrate either in the gas form, through a gas-injection system, or in thin-film form, through spin coating. Recently, it has been found that the electrical resistance of spin-coated PdAc organometallic films submitted to FIB irradiation can be metallic at an optimized ion dose, without the need of any post-processing purification step. On the other hand, if such PdAc films are submitted to low-dose focused electron beam irradiation (FEB), they become an insulating material. Here, we combine the use of FIB and FEB irradiation to produce (additively) micro- and nano-structured materials that act as gates in electronic devices. Three different gate configurations have been explored, and applied to suppress superconductivity in metallic nanowires through electric-field effects, including lateral and top gating. This new fabrication technique for investigation of electrical gating effects at the micro- and nano-scales stands out by its precision and resolution (due to the use of focused charged beams), by the absence of sacrificial resist layers, and by the process speed.