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  Carbon nanotube-based electronic devices made by electrolytic deposition and applications thereofUSPTO Application #: 20060065887Title: Carbon nanotube-based electronic devices made by electrolytic deposition and applications thereof Abstract: Carbon nanotube-based devices made by electrolytic deposition and applications thereof are provided. In a preferred embodiment, the present invention provides a device comprising at least one array of active carbon nanotube junctions deposited on at least one microelectronic substrate. In another preferred embodiment, the present invention provides a device comprising a substrate, at least one pair of electrodes disposed on the substrate, wherein one or more pairs of electrodes are connected to a power source, and a bundle of carbon nanotubes disposed between the at least one pair of electrodes wherein the bundle of carbon nanotubes consist essentially of semiconductive carbon nanotubes. In another preferred embodiment, a semiconducting device formed by electrodeposition of carbon nanotubes between two electrodes is provided. The invention also provides preferred methods of forming a semiconductive device by applying a bias voltage to a carbon nanotube rope. The plurality of metallic single-wall carbon nanotubes are removed (e.g., by application of bias voltage) in an amount sufficient to form the semiconducting device. The devices of the invention include, but not limited to, chemical or biological sensors, carbon nanotube field-effect transistors (CNFETs), tunnel junctions, Schottky junctions, and multi-dimensional nanotube arrays. (end of abstract) Agent: Dickstein Shapiro Morin & Oshinsky LLP - Washington, DC, US Inventors: Thomas Tiano, John Gannon, Charles Carey, Brian Farrell, Richard Czerw USPTO Applicaton #: 20060065887 - Class: 257020000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Thin Active Physical Layer Which Is (1) An Active Potential Well Layer Thin Enough To Establish Discrete Quantum Energy Levels Or (2) An Active Barrier Layer Thin Enough To Permit Quantum Mechanical Tunneling Or (3) An Active Layer Thin Enough To Permit Carrier Transmission With Substantially No Scattering (e.g., Superlattice Quantum Well, Or Ballistic Transport Device), Heterojunction, Quantum Well, Superlattice, Field Effect Device The Patent Description & Claims data below is from USPTO Patent Application 20060065887. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 60/557,118 filed on Mar. 26, 2004 which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION [0003] The present invention relates to carbon nanotube-based electronic devices. In particular, this invention relates to carbon nanotube-based electronic devices made by electrolytic deposition. BACKGROUND OF THE INVENTION [0004] The semiconductor industry is facing increasingly difficult technological challenges, as it moves into the production of features at sizes below 100 nanometers. Particular challenges are to achieve affordable scaling and achieve affordable lithography with dimensions below 100 nanometers, utilize new materials and structures, and achieve gigahertz frequency operations and very high device densities on chips. There is a lack of consensus in the industry about how to solve the fabrication challenges that lie beyond the 100 nanometer barrier. The problem confronting the industry is that the dominant technology used to make chips, optical lithography, uses light to form patterns on silicon. Below 100 nanometers, the wavelength of light that is, typically, employed in chip production (193 nanometers and 157 nanometers) is too large to be useful. Several candidate technologies are currently vying for selection as successors to optical lithography. These include extreme ultraviolet lithography (EUV), an electron beam method called scalpel, and x-ray lithography. None has yet emerged as the preferred choice. [0005] It is widely recognized that the development of molecular electronics based on carbon nanotubes would enable logic devices to be built that have billions of transistors. Such computers would be orders of magnitude more powerful than today's machines. In order for this to become a reality, a method must be found to mass produce the molecular electronic devices. Scanning probe methods have proven feasible for fabricating single devices one nanotube at a time, but no way has been found yet to speed up the process sufficiently to make billions of transistors practical. Chemical based self-assembly processes have also been suggested, but so far, only the simplest structures have been built by use of this method. The problem of combining different materials and assembling molecular electronic devices with specific features remains a significant challenge. Therefore, it would be desirable to demonstrate the feasibility of cost-effectively fabricating carbon nanotube molecular electronic devices that have a nanosize diameter (e.g., 0.7-50 nanometers), micron-to-submicron-sized length (e.g., 100-1000 nanometers), and a gate structure that is a few nanometers long (e.g., 0.1-5 nanometers). [0006] A nanotube or nanotube bundle/rope is typically much longer that 1 nanometer. Therefore, many inputs or junctions are needed along the length of each nanotube or nanotube rope to achieve desired nanoscale density. Nanotube junctions, or active nanotube junctions, are locations or points were nanotubes are in close proximity to each other and can be modified electrically. [0007] Theoretical work by Chico et al., "Pure carbon nanoscale devices: nanotube heterojunctions," Physical Review Letters, 1996, has suggested that introducing pentagon-heptagon pair defects into otherwise hexagonal nanotube structure may create junctions between two topologically or electrically different nanotubes, as bases for nanoscale nanotube devices. S. Saito, "Carbon nanotubes for next generation electronic devices," Science, 1997, describes possible theoretical designs of a carbon nanotube that may function as a molecular electronic device. Those and other similar theoretical works outline the possibility to use carbon nanotubes as molecular devices, but fail to propose a design of such device and a method of its fabrication. [0008] Collins et al., "Nanoscale electronic devices on carbon nanotubes," Fifth Foresight Conference on Molecular Nanotechnology, 1997, have demonstrated experimentally the rectification properties of single-wall carbon nanotubes. This work also fails to propose a design for carbon nanotube molecular electronic devices and a method of fabrication. [0009] Therefore, in order to overcome current fabrication approaches that are expensive and impractical (e.g., placing individual nanotubes on a substrate with an atomic force microscope), a method is needed to mass produce carbon nanotube-based electronic devices in a manner that is efficient, cost-effective, and scalable. BRIEF SUMMARY OF THE PRESENT INVENTION [0010] The present invention is carbon nanotube-based electronic devices made by electrolytic deposition and applications thereof. The present invention includes nanotube-based electronic devices that are made by electrolytic deposition, such as, but not limited to, chemical or biological sensors, carbon nanotube field-effect transistors (CNFETs), tunnel junctions, Schottky junctions, and a two-dimensional array of nanotube junctions that is suitable for use as a building block in a signal processing application that requires high circuit density. [0011] The present invention includes a novel method of fabricating single-wall nanotube devices that includes the combination of an electrolytic deposition process, followed by an operation to selectively "burn out" the percolated metallic nanotubes and, thereby, form a semiconducting nanotube-based electronic device. [0012] Furthermore, the fabrication method of the present invention provides an efficient, cost-effective process for mass producing nanotube-based electronic devices that is scalable. [0013] In a preferred embodiment, the present invention provides a device comprising at least one array of active carbon nanotube junctions deposited on at least one microelectronic substrate. In another preferred embodiment, the present invention provides a device comprising a substrate, at least one pair of electrodes disposed on the substrate, wherein one or more pairs of electrodes are connected to a power source, and a bundle of carbon nanotubes disposed between at least one pair of electrodes wherein said bundle consists essentially of semiconductive carbon nanotubes. In another embodiment, the bundle of carbon nanotubes consists of semiconductive carbon nanotubes and isolated metallic nanotubes. In another preferred embodiment, a semiconducting device formed by electrodeposition of carbon nanotubes between two electrodes is provided. [0014] The invention also provides preferred methods of forming a semiconductive device by ramping a bias voltage across a single-wall carbon nanotube rope. The single-wall carbon nanotube rope preferably comprises a plurality of semiconducting single-wall carbon nanotubes and a plurality of metallic single-wall carbon nanotubes. The plurality of metallic single-wall carbon nanotubes are removed (e.g., by application of a bias voltage) in an amount sufficient to form the semiconducting device. [0015] It is an object of the invention to provide electrical devices that are formed by carbon nanotube technology. [0016] It is another object of this invention to provide an economic fabrication process for mass producing carbon nanotube electrical devices. [0017] It is yet another object of this invention to provide increased circuit density, by use of carbon nanotube devices. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 illustrates a side view of a single-wall carbon nanotube device in its simplest form in accordance with an embodiment of the invention. [0019] FIG. 2 is a flow diagram of an exemplary method of cost-effectively mass producing semiconducting single-wall carbon nanotube devices, by use of electrolytic deposition, in combination with a "burn out" operation. [0020] FIG. 3A illustrates a top view of a single-wall carbon nanotube device, formed by the exemplary method of FIG. 2. Continue reading... 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