VO2 microrods synthesized from V2O5 thin films

Abstract

Self-assembled single crystal VO2 microrods (MRs) with a length up to 600 µm have been synthesized on Si and sapphire substrates by the annealing of V2O5 thin films. The nucleation and growth of VO2 MRs from V2O5 thin films were investigated. The morphology and microstructure evolutions of the intermediate phases during the reduction process were characterized by SEM, HRTEM, XPEEM, and Raman spectroscopy. The results have shown that the conversion of V2O5 thin films to VO2 MRs is dominated by a melting-nucleation-growth mechanism. The growth of VO2 MRs can be controlled by V2O5 melting process and a consistent feeding of V2O5 liquids to the growing VO2 MR would lead to ultra-long VO2 MRs. Further, epitaxial growth of VO2 MRs can be induced by using an r-cut sapphire substrate.