Carbon nanotubes as field emission sources (original) (raw)
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Current Applied Physics, 2001
A microelectronic parallel electron-beam lithography system using an array of ®eld emitting microguns is currently being developed. This paper investigates the suitability of various carbon based materials for the electron source in this device, namely tetrahedrally bonded amorphous carbon (ta-C), nanoclustered carbon and carbon nanotubes. Ta-C was most easily integrated into a gated ®eld emitter structure and various methods, such as plasma and heavy ion irradiation, were used to induce emission sites in the ta-C. However, the creation of such emission sites at desired locations appeared to be dicult/random in nature and thus the material was unsuitable for this application. In contrast, nanoclustered carbon material readily ®eld emits with a high site density but the by-products from the deposition process create integration issues when using the material in a microelectronic gated structure. Carbon nanotubes are currently the most promising candidate for use as the emission source. We have developed a high yield and clean (amorphous carbon by-product free) PECVD process to deposit single free standing nanotubes at desired locations with exceptional uniformity in terms of nanotube height and diameter. Field emission from an array of nanotubes was also obtained.
Diamond and Related Materials, 2010
The present study investigates the patterned growth of carbon nanotubes (CNTs) by microwave plasma assisted chemical vapor deposition (MPCVD) and their field emission (FE) properties. The nanosphere monolayers were used as a mask for deposition of ultrathin (~3 nm) cobalt (Co) layer by DC sputtering. Periodic arrays of Co catalyst islands were obtained after the removal of spheres. Microscopic and Raman spectroscopic studies revealed the patterned growth of multiwall CNTs on catalyst islands. The CNTs length was around 10 µm and diameter was of 40-60 nm. The field emission properties were also compared with I-V characteristics of the un-patterned CNTs grown under the same conditions. The onset fields for un-patterned and patterned samples were nearly the same, 0.64 V/µm and 0.67 V/µm, respectively for a 10 µA current.
Growth of vertically aligned arrays of carbon nanotubes for high field emission
Thin Solid Films, 2008
Vertically aligned multi-walled carbon nanotubes have been grown on Ni-coated silicon substrates, by using either direct current diode or triode plasma-enhanced chemical vapor deposition at low temperature (around 620 °C). Acetylene gas has been used as the carbon source while ammonia and hydrogen have been used for etching. However densely packed (∼ 10 9 cm − 2 ) CNTs were obtained when the pressure was ∼ 100 Pa. The alignment of nanotubes is a necessary, but not a sufficient condition in order to get an efficient electron emission: the growth of nanotubes should be controlled along regular arrays, in order to minimize the electrostatic interactions between them. So a three dimensional numerical simulation has been developed to calculate the local electric field in the vicinity of the tips for a finite square array of nanotubes and thus to calculate the maximum of the electron emission current density as a function of the spacing between nanotubes. Finally the triode plasmaenhanced process combined with pre-patterned catalyst films (using different lithography techniques) has been chosen in order to grow regular arrays of aligned CNTs with different pitches in the micrometer range. The comparison between the experimental and the simulation data permits to define the most efficient CNT-based electron field emitters.
6.1: Invited Paper: Design of Carbon Nanotubes for Field Emission Applications
SID Symposium Digest of Technical Papers, 2009
Field emission from CNTs can be applied to many technologies because of their high current carrying capability, chemical inertness, physical strength and high aspect ratio. Depending upon their applications it can be more advantageous to use either individual tubes or arrays of tubes. Multiwall tubes or single wall tubes can also be utilised and in some instances aligned tubes are also necessary to provide the field emission currents required. This paper will present work on the optimisation of Carbon Nanotubes for applications including, field emission displays, electron microscopes, x-rays, and microwave sources.
Utilization of carbon nanotube and diamond for electron field emission devices
17th IEEE International Conference on Micro Electro Mechanical Systems. Maastricht MEMS 2004 Technical Digest, 2004
We are currently developing a monolithic electron field emission device and integrated electron optic components for multi-electron beam lithography microsystems basing on a SO1 (Silicon On Insulator) wafer. In the Transducer'03 conference, we have reported the concept, simulation, fabrication, emission and focusing characteristics of the device with Pt, MO emitters [I].
Electron-beam-induced deposition with carbon nanotube emitters
Applied Physics Letters, 2002
Electron-beam-induced deposition ͑EBID͒ is performed with multiwalled carbon nanotube emitters that are assembled to atomic force microscope cantilevers through nanorobotic manipulations. A typical experiment shows that under 120 V bias, field emission current 2 A occurs from a nanotube emitter. In comparison with conventional EBID with a Schottky-type electron gun of a field-emission scanning electron microscope ͑FESEM͒ in the same vacuum chamber, the deposition rate of the nanotube emitter reaches up to 12.2% of that of FESEM although the bias and the emission current are only 0.8% and 1.9% of those of FESEM ͑15 kV and 106 A͒. The concept of parallel EBID is also presented.