A new approach to the fabrication of VO2 nanoswitches with ultra-low energy consumption

A new approach for the formation of free-standing vertical resistive nanoswitches based on VO2 nanocrystals (NCs) with embedded conductive nanosharp Si tips is demonstrated in the present article. This approach consists in the chemical vapor deposition synthesis of VO2 NCs on the apices of sharp conductive nanotips formed on a Si substrate by the standard methods of planar silicon technology. The amplification of the electric field and current density at the tip apex inside a high-quality VO2 NC leads to a record-breaking reduction of switching voltage (by a factor of 20–70) in comparison with conventional geometry devices with planar contacts. Our pulse measurements showed that the extremely low energy equal to 4.2 fJ was consumed for the switching in such NCs, and the total number of switching cycles in one NC without degradation exceeded 1011. The proposed approach can be extended to the formation of large arrays of such nanoswitches. We showed that periodic arrays of individual VO2 NCs were selectively synthesized on sharp Si tips. The nanosizes of the switches, ultra-low power consumption for switching and the possibility of forming dense arrays of such objects make the fabricated nanoswitches promising devices for future neuromorphic systems.