T. Tyler

High field emission reproducibility and stability of carbon nanosheets and nanosheet-based backgated triode emission devices

The authors have characterized field emission properties of freestanding, 1nm thick graphene layers, called carbon nanosheets (CNSs), which were grown perpendicular to the growth surface using a radio-frequency plasma-enhanced chemical vapor deposition technique. The CNSs are metallic impurity-free and have uniform height distribution (standard deviation of 200h at 1.3mA emission current level. Over this time, no degradation has been observed, the variability of the individual I-V curves is small among 7216 voltage cycles, and the standard deviation at the maximum current was no more than 2.3%. A nanosheet-based backgated triode emission device has been developed to take advantage of the nanosheet field emission performance. Prototype devices have confirmed triode operation and stable electron emission.

Nanodiamond particles forming photonic structures.

Colloid suspensions of irregularly shaped, highly charged detonation nanodiamond particles are found to have unexpected optical properties, similar to those of photonic crystals. This finding is all the more surprising since the particles used in this work are far more polydisperse than those typically forming photonic crystals. Intensely iridescent structures have been fabricated using the centrifugation of aqueous suspensions of nanodiamonds.

Vacuum microelectronic devices and vacuum requirements

With the emergence of microfabrication and thin film deposition techniques developed by the semiconductor industry, it became apparent that miniature vacuum microelectronic devices could be developed. Using approaches as diverse as controlled evaporation, chemical etching (both wet isotropic and anisotropic and dry plasma etching) and controlled oxidation, sharp tips were formed in both metals and semiconductor materials with a radius of less than 50 nm. When integrated with a gate electrode, field enhancement at the tip showed the promise of very high field emission electron currents, especially when arrays of more than one million tips per square centimeter could be produced. Even though currents above 1 mA have been achieved, vacuum microelectronic devices have not been adapted into widespread use. The vacuum environment of the device leads to changes in emission performance and premature failure that has limited the acceptance of the devices. Numerous approaches have been explored to improve and maint...

Buried-Line Back-Gated Triode Field Emission Devices

Reported in this paper is recent work on a new type of back-gated triode device. Fabrication of the device and modeled performance predictions are discussed

High brightness field emission from carbon nanosheets and back-gated devices

A 2D atomically thin nanostructure, carbon nanosheet, was synthesized via radio frequency plasma enhanced chemical vapor deposition. Carbon nanosheets are free-standing, and have flat surface morphologies, atomically thin edges, and defective graphitic structures. Field electron emission from carbon nanosheets was measured under diode mode. Carbon nanosheets samples have turn-on fields of 5-10 V/mum, and can yield a total emission current of 28 mA from an area of 8 times 8 mm2 and an emission current density of ~2 mA/mm2 from an area of 1 times 1 mm2. Back-gated triode devices using carbon nanosheets as cathode material were also designed, fabricated, and tested under triode mode. A total emission current of 1.3 mA was achieved from one single device.

Milliamp-Class, Back-Gated, Triode Field Emission Devices Based on Free-Standing, Two-Dimensional Carbon Nanostructures

In this presentation we discuss recent results using carbon nanosheets (CNS) as the field emission source in a back gated device for high current applications

High current field emission from graphitic carbon nanosheets

A novel nanostructured carbon material termed carbon nanosheet, which is to be utilized in a high current (milliamp-level) field emission cathode, is presented. Carbon nanosheet (CNS) consists of vertically aligned graphitic sheets, with each sheet consisting of only a few graphite planes. The width of the individual sheets, a few nanometers thick, provides a large enhancement factor for low threshold-field emission. In contrast, the CNS prove to be quite rigid, being able to withstand photolithographic processing, making CNS a cathode material compatible with current micro-electronic device fabrication techniques. Utilizing an approach curve method, electron emission threshold fields of less than 5/V/spl mu/m are routinely achieved, as are current densities /spl sim/1 mA/mm/sup 2/ with no sample degradation, and with total emission currents greater than 2 mA. Carbon nanosheets are currently being applied in novel back-gated field emission devices.