title: Synthesis and field emission properties of ultra-nanocrystalline diamond fibers and helices.
abstract: We propose a novel template method for large scale synthesis of Ultra-Nanocrystalline Diamond (UNCD) fibres and helices with lengths of thousands of microns and diameters ranging from 0.5 to 5 microm: (i) Large quantities of submicrometer- or nanometer-diameter silica (a-SiO2) nanostructures, with lengths in the order of 2 to 4 mm, were synthesized by Vapor-Liquid-Solid (VLS) method; (ii) UNCD coating of as-synthesized a-SiO2 micro- or nanonanostructures by Microwave Plasma Chemical Vapour Deposition (MPCVD) technique in hydrogen-deficient condition. Electron Field Emission (EFE) of as-synthesized UNCD structures was observed with a threshold field of 3.4 V/microm. These micro- or nanostructures may find potential applications in high power electronics, vertical field-effect transistors in vacuum electronics, heat sinks in microelectronics and structural materials in Micro- and Nano-Electro-Mechanical Systems (MEMS/NEMS). The successful preparation of various types of UNCD structures suggests that this templating process can be used for a wide range of materials.
authors.affiliation: Center for Mechanical Technology and Automation, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: M K
authors.initials: MK
authors.lastname: Singh
authors.forename: E
authors.initials: E
authors.lastname: Titus
authors.forename: M G
authors.initials: MG
authors.lastname: Willinger
authors.forename: J
authors.initials: J
authors.lastname: Grácio