On the evaluation of field emission parameters of V2O5 and TiO2 nanostructure cathodes

Abstract

The self-assembled V _2 O _5 and TiO _2 nanowires are prepared hydrothermally from vanadium (V) hydroxylamido complex and titanium oxide powder, respectively, and studied for their crystalline phase, morphology, and electron emission characteristics. V _2 O _5 is shown to exhibit an orthorhombic phase with preferential growth of the (010) face along the [010] direction; wire size being diameter 100–400 nm, and length several micrometers. TiO _2 nanowires depict a monoclinic β -phase with a typical diameter of ∼ 30 nm. Their bundles serve as potential cathodes giving electron emission following the Fowler–Nordheim (F-N) mechanism but from infinitely small areas with large field enhancement factors. In comparison, β -TiO _2 provides better emission characteristics at similar operating parameters (e.g., low threshold voltage 250–400 V and current density 10 ^9 −10 ^13 A m ^−2 ). The unique properties (viz., tip geometry, roughness, and local field enhancement) of one-dimension (1D) nanowires make them prospective candidates for high-brightness electron sources and development of the display devices [1–7]. A simple procedure developed by the authors is applied successfully in actual evaluation of the field emission parameters from the current–voltage data. This involves F-N formulation with physical considerations like variation of work function, effective emission area, and field enhancement factor [31].

Keywords

• V2O5 nanobundles
• TiO2 nanowires
• field emission
• fowler-nordheim plot
• current-voltage characteristics
• electron emission characteristics