Growth of ordered arrays of vertical free-standing VO2 nanowires on nanoimprinted Si

Abstract

In recent years, the synthesis and study of individual single-crystal VO2 nanowires (NWs) have been attracting much interest due to the unique properties of the material related with the single-domain metal-insulator phase transition in such NWs. Although single-crystal VO2 NWs offer much promise for practical applications, the lack of a technology for forming NW arrays and, especially, ordered arrays of VO2 NWs still does not permit the mass fabrication of VO2-based devices and materials. Here, we break this barrier and synthesized ordered arrays of free-standing single-crystal monoclinic VO2 NWs. Vertically aligned, strongly periodic VO2 NWs were obtained in a chemical vapor deposition process used to grow VO2 on nanoimprinted Si substrate. Indicative of a high quality of obtained NW is a sharp rise of conductivity at the phase transition in VO2 reaching in magnitude four orders as well as a pronounced faceting of the crystals confirmed by x-ray diffraction measurements. Our approach paves the way toward a broad application of VO2 single crystals with desired sizes, shapes, and aspect ratios in various fields of nanophotonics and nanoelectronics, and in smart materials.