Formation of vanadium dioxide nanocrystal arrays via post-growth annealing for stable and energy-efficient switches

The abrupt and reversible semiconductor-metal phase transition in vanadium dioxide nanocrystals has attracted considerable attention for potential applications in oxide electronics, including neuromorphic systems. This study presents a systematic investigation of post-growth annealing conditions for the formation of single VO2 M-phase nanocrystals arrays from VOx films synthesized by atomic layer deposition. The composition of the initial VOx films and the annealing parameters were found to significantly affect the morphology, phase composition and electrical properties of the obtained single nanocrystal arrays. Our results demonstrate that the formation of VO2 M-phase nanocrystal arrays occurs at annealing temperatures of 650 °C and above, irrespective of the initial film composition. More homogeneous in size nanocrystals are formed from initial VOx films with higher V+4 content. The structures with the initial V+4 content of 60 % annealed at 650 °C for 2 h demonstrates the resistive switching with an energy less than 150 fJ, and a total number of stable switching cycles more than 101⁰. Our results pave the way for the novel energy-efficient nanoelectronic and nanophotonic devices based on VO₂ nanoparticles. [Display omitted] •The initial composition of ALD VOx films and post-growth annealing parameters were investigated to form VO2 nanocrystals.•Uniform and energy-efficient VO2 nanocrystals were formed from films with 60% of V+4 annealed at 650 °C for 2 hours.•The threshold voltage of resistive switching in VO2 nanocrystals decreases as a result of second annealing.•VO2 nanocrystal arrays have the high stability of more than 1010 cycles and resistive switching energy less than150 fJ.