Brian D. Hunt

Bio: Brian D. Hunt is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Carbon nanotube & Josephson effect. The author has an hindex of 22, co-authored 68 publications receiving 2078 citations. Previous affiliations of Brian D. Hunt include United States Naval Research Laboratory & Jet Propulsion Laboratory.

Pattern-aligned carbon nanotube growth and tunable resonator apparatus

Abstract: A tunable nanomechanical oscillator device and system is provided. The nanomechanical oscillator device comprising at least one nanoresonator, such as a suspended nanotube, designed such that injecting charge density into the tube (e.g. by applying a capacitively-cuopled voltage bias) changes the resonant frequency of the nanotube, and where exposing the resonator to an RF bias induces oscillitory movement in the suspended portion of the nanotube, forming a nanoscale resonator, as well as a force sensor when operated in an inverse mode. A method of producing an oriented nanoscale resonator structure with integrated electrodes is also provided.

Carbon nanotube Schottky diodes using Ti-Schottky and Pt-ohmic contacts for high frequency applications

Abstract: We have demonstrated Schottky diodes using semiconducting single-walled nanotubes (s-SWNTs) with titanium Schottky and platinum Ohmic contacts for high-frequency applications. The diodes are fabricated using angled evaporation of dissimilar metal contacts over an s-SWNT. The devices demonstrate rectifying behavior with large reverse bias breakdown voltages of greater than 15 V. To decrease the series resistance, multiple SWNTs are grown in parallel in a single device, and the metallic tubes are burnt-out selectively. At low biases these diodes showed ideality factors in the range of 1.5 to 1.9. Modeling of these diodes as direct detectors at room temperature at 2.5 terahertz (THz) frequency indicates noise equivalent powers (NEP) potentially comparable to that of the state-of-the-art gallium arsenide solid-state Schottky diodes, in the range of 10-13 W(square root)xHz.

Method of producing regular arrays of nano-scale objects using nano-structured block-copolymeric materials

Abstract: A method of forming a periodic array of nano-scale objects using a block copolymer, and nano-scale object arrays formed from the method are provided. The method for forming the arrays generally includes the steps of depositing a block copolymer of at least two blocks on a substrate to form an ordered meso-scale structured array of the polymer materials, forming catalytic metal dots based on the meso-scale structure, and growing nano-scale objects on the catalytic dots to form an ordered array of nano-scale objects.

Electromechanical carbon nanotube switches for high-frequency applications

Abstract: We describe the fabrication and characterization of a nanoelectromechanical (NEM) switch based on carbon nanotubes. Our NEM structure consists of single-walled nanotubes (SWNTs) suspended over shallow trenches in a SiO(2) layer, with a Nb pull electrode beneath. The nanotube growth is done on-chip using a patterned Fe catalyst and a methane chemical vapor deposition (CVD) process at 850 degrees C. Electrical measurements of these devices show well-defined ON and OFF states as a dc bias up to a few volts is applied between the CNT and the Nb pull electrode. The CNT switches were measured to have speeds that are 3 orders of magnitude higher than MEMS-based electrostatically driven switches, with switching times down to a few nanoseconds, while at the same time requiring pull voltages less than 5 V.

Carbon nanotube array rf filter

Abstract: A tunable nanomechanical filter system (10) comprising an array of nanofeatures (18), such as nanotubes, where the nanofeatures (18) are in signal communication with means for inducing a difference in charge density in the nanofeature (18) such that the mechanical resonant frequency of the nanofeature (18) can be tuned, and where the nanofeature (18) is in signal communication with a waveguide (14) or other RF bias conduit such that an RF signal having a frequency corresponding to the mechanical resonant frequency of the array will couple to the array thereby inducing resonant motion in the array of nanofeatures (18), and subsequently coupling to an output waveguide (16), forming a nanoscale RF filter (10) is provided. A method of producing a nanoscale RF filter (10) structure controllably positioned and oriented with a waveguide (14/16) and integrated electrodes (20) is also provided.

Semiconductor device, and manufacturing method thereof

Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Medium scale carbon nanotube thin film integrated circuits on flexible plastic substrates

Abstract: The present invention provides device components geometries and fabrication strategies for enhancing the electronic performance of electronic devices based on thin films of randomly oriented or partially aligned semiconducting nanotubes. In certain aspects, devices and methods of the present invention incorporate a patterned layer of randomly oriented or partially aligned carbon nanotubes, such as one or more interconnected SWNT networks, providing a semiconductor channel exhibiting improved electronic properties relative to conventional nanotubes-based electronic systems.

The flux-line lattice in superconductors

Abstract: Magnetic flux can penetrate a type-II superconductor in the form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons) each carrying a quantum of magnetic flux phi 0=h/2e. These tiny vortices of supercurrent tend to arrange themselves in a triangular flux-line lattice (FLL), which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-Tc superconductors (HTSCs) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSCs the FLL is very soft mainly because of the large magnetic penetration depth lambda . The shear modulus of the FLL is c66~1/ lambda 2, and the tilt modulus c44(k)~(1+k2 lambda 2)-1 is dispersive and becomes very small for short distortion wavelengths 2 pi /k<< lambda . This softness is enhanced further by the pronounced anisotropy and layered structure of HTSCs, which strongly increases the penetration depth for currents along the c axis of these (nearly uniaxial) crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may `melt` the FLL and cause thermally activated depinning of the flux lines or ofthe two-dimensional `pancake vortices` in the layers. Various phase transitions are predicted for the FLL in layered HTSCs. Although large pinning forces and high critical currents have been achieved, the small depinning energy so far prevents the application of HTSCs as conductors at high temperatures except in cases when the applied current and the surrounding magnetic field are small.