Fabrication and characterization of novel nanoscale field emission arrays

In this thesis we have demonstrated novel nanoscale cold cathode devices based on rare-earth monosulfides, gold nano pinetree like and carbon nano pearl arrays. We first developed a MEMS based cold cathode device based on pulsed laser deposition (PLD) of lanthanum monosulfide (LaS). The device exhibited a largest field emission (FE) current of 5x10-7 A which is suitable for flat panel displays. It can also be used to develop a three terminal device providing gate control of the field emission current. Then, in an effort to fabricate nanoscale arrays of LaS for efficient field emission, we discovered the formation of trimodal arrays where three different nanoscale arrays of LaS-nanodots, nanodomes and nanowires have been simultaneously fabricated by PLD of LaS on flexible self-assembled nanoporous alumina templates. The nanodots with a density of 1010/cm 2 and the nanodomes with a density of 109/ cm2 are formed on the surface of template while the nanowires are formed inside the pores with a density of 1010/ cm2. The LaS nanoscale features formed on the surface of the templates acted as efficient field emitters by reducing the threshold voltage by ∼3.5 times for the same amount of field emitted current compared to the LaS thin films deposited on silicon substrates.;During the process of investigating the formation of trimodal arrays of LaS we have observed three distinct unique nanoscale features all formed on the surface of the nanoporous alumina templates. The first feature is the self assembly of carbon nanopearls in the form of nanotentacles and nanonecklaces on an array of nickel nanodots and nanodomes. The second feature is the nanopinetree like structures formed by e-beam evaporation of gold onto the alumina template. Both these features have emitted stable field emission current. The third feature is the nanoblade like structures formed by e-beam evaporation of nickel on the alumina template. A stable field emission current could not be obtained which can be explained by the reactivity of nickel to the adsorbed species. While the CNP nanotentacle and Au nanopinetree like features can be used to form novel inexpensive high density cold cathodes, the nickel nanoblade like features cannot be used as planar cathodes.