Diamond for use in Cold Cathode Devices, including Displays
In collaboration with colleagues in the Physics Dept, we have been studying the so called 'negative electron affinity' of diamond. This is a property which enables diamond to emit electrons from its surface without requiring large voltages. This makes possible applications such as microelectronic devices, sensors, and flat panel displays. A schematic diagram of how a diamond-based cold cathode field emitting display might be fabricated is shown below.
We are working on measuring the I-V characteristics of diamond films grown under a number of different deposition conditions, and by a variety of diverse methods, such as polycrystalline and nanocrystalline CVD diamond made by Hot Filament and Microwave reactors, diamond-like carbon (doped and undoped) made by RF plasma deposition methods, and ta-C films made by laser ablation of graphite.
We have recently developed a process to make diamond-coated carbon nanotubes (CNTs), which involves electrospray seeding 'forests' of vertically aligned multiwall CNTs which causes the CNTs to clump together and join at their tips to produce 'teepee' structures (photo, right). Once coated with a thin layer of B-doped CVD diamond, these composite teepees show excellent field emission characteristics with hugely extended lifetimes.
- Y. Zou, P.W. May, S.M.C. Vieira, N.A. Fox, "Field emission from diamond-coated multiwalled carbon nanotube 'teepee' structures", J. Appl. Phys. 112 (2012) 044903.
- H. Zanin, P.W. May, M.H.O.M. Hamanaka, E.J. Corat, "Field emission from hybrid diamond-like carbon and carbon nanotube composite structures", ACS Applied Materials & Interfaces 5 (2013) 12238-12243.