Cross-Linked Carbon Nanotube Heat Spreader

2014 ◽  
Vol 1752 ◽  
pp. 131-136
Author(s):  
Gregory A. Konesky
Keyword(s):  
Thermal Conductivity ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Ion Beam ◽  
Healing Process ◽  
High Surface ◽  
High Surface Area ◽  
Self Healing ◽  
Spreading Effect ◽  
Heat Spreaders

ABSTRACTAmong the exceptional properties of isolated individual carbon nanotubes (CNTs), exceptional thermal conductivity along their axis has been demonstrated, However they have also shown poor thermal transfer between adjacent CNTs. Thick bundles of aligned CNTs have been used as heat pipes, but the thermal input and output power densities are the same, providing no heat spreading effect. We demonstrate the use of energetic argon ion beams to join overlapping CNTs in a thin film to form an interpenetrating network with an isotropic thermal conductivity of 2150 W/m K. Such thin films may be used as heat spreaders to enlarge the thermal footprint of laser diodes and CPU chips, for example, for enhanced cooling. At higher ion energies and fluence, the CNTs appear to collapse and reform, aligned parallel to the ion beam axis, and form dense high aspect ratio tapered structures. The high surface area of these structures lends themselves to applications in energy storage, for example. We consider the mechanisms of energetic ion interaction with CNTs and junction formation of two overlapping CNTs during the subsequent self-healing process, as well as the formation of high aspect ratio structures under more extreme conditions

scholarly journals Atomic Layer Deposition of GdCoO3 and Gd0.9Ca0.1CoO3

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 24
Author(s):  
Marion Duparc ◽  
Henrik Hovde Sønsteby ◽  
Ola Nilsen ◽  
Anja Olafsen Sjåstad ◽  
Helmer Fjellvåg
Keyword(s):  
Thin Films ◽  
Aspect Ratio ◽  
Atomic Layer Deposition ◽  
High Aspect Ratio ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Layer ◽  
Oxidation Catalysis ◽  
Post Annealing ◽  
Layer Deposition

Thin films of the catalytically interesting ternary and quaternary perovskites GdCoO3 and Gd0.9Ca0.1CoO3 are fabricated by atomic layer deposition using metal β-diketonates and ozone as precursors. The resulting thin films are amorphous as deposited and become single-oriented crystalline on LaAlO3(100) and YAlO3(100/010) after post-annealing at 650 °C in air. The crystal orientations of the films are tunable by choice and the orientation of the substrate, mitigated through the interface via solid face epitaxy upon annealing. The films exhibit no sign of Co2+. Additionally, high-aspect-ratio Si(100) substrates were used to document the suitability of the developed process for the preparation of coatings on more complex, high-surface-area structures. We believe that coatings of GdCoO3 and Gd1−xCaxCoO3 may find applications within oxidation catalysis.

Antibody immobilization for ZnO nanowire based biosensor application

2014 ◽  
Vol 1675 ◽  
pp. 33-39 ◽  
Author(s):  
Ankur Gupta ◽  
Monalisha Nayak ◽  
Deepak Singh ◽  
Shantanu Bhattacharya
Keyword(s):  
Zinc Oxide ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Surface ◽  
High Surface Area ◽  
Solution Chemistry ◽  
Surface Topology ◽  
Antibody Activity ◽  
Antibody Immobilization ◽  
Protein Assay

ABSTRACTDue to the high surface area and good bio-compatibility of nano structured ZnO, it finds good utility in biosensor applications. In this work we have fabricated highly dense ZnO nano bundles with the assistance of self assembled poly methylsilisesquoxane (PMSSQ) matrix which has been realized in a carpet like configuration with implanted ZnO nano-seeds. Such high aspect ratio structures (∼50) with carpet like layout have been realized for the first time using solution chemistry. Nanoparticles of PMMSQ are mixed with a nano-assembler Poly-propylene glycol (PPG) and Zinc Oxide nanoseeds (5-15 nm). The PPG acts by assembling the PMSSQ nanoparticles and evaporates from this film thus creating the highly porous nano-assembly of PMMSQ nanoparticles with implanted Zinc Oxide seeds. Nano-wire bundles with a high overall surface roughness are grown over this template by a daylong incubation of an aqueous solution of hexamethylene tetra amine and Zinc nitrate. Characterization of the fabricated structures has been extensively performed using FESEM, EDAX, and XRD. We envision these films to have potential of highly dense immobilization platforms for antibodies in immunosensors. The principle advantage in our case is a high aspect ratio of the nano-bundles and a high level of roughness in overall surface topology of the carpet outgrowing the zinc-oxide nanowire bundles. Antibody immobilization has been performed by modifying the surface with protein-G followed by Goat anti salmonella antibody. Antibody activity has been characterized by using 3D profiler, Bio-Rad Protein assay and UV-Visible spectrophotometer.

Fluorocarbon Precursor for High Aspect Ratio via Milling in Focused Ion Beam Modification of Integrated Circuits

2004 ◽  
Author(s):  
Valery Ray
Keyword(s):  
Side Effects ◽  
Aspect Ratio ◽  
Integrated Circuits ◽  
High Aspect Ratio ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Enabling Technology ◽  
Si Substrate ◽  
Ion Beam Modification ◽  
The Past

Abstract Gas Assisted Etching (GAE) is the enabling technology for High Aspect Ratio (HAR) circuit access via milling in Focused Ion Beam (FIB) circuit modification. Metal interconnect layers of microelectronic Integrated Circuits (ICs) are separated by Inter-Layer Dielectric (ILD) materials, therefore HAR vias are typically milled in dielectrics. Most of the etching precursor gases presently available for GAE of dielectrics on commercial FIB systems, such as XeF2, Cl2, etc., are also effective etch enhancers for either Si, or/and some of the metals used in ICs. Therefore use of these precursors for via milling in dielectrics may lead to unwanted side effects, especially in a backside circuit edit approach. Making contacts to the polysilicon lines with traditional GAE precursors could also be difficult, if not impossible. Some of these precursors have a tendency to produce isotropic vias, especially in Si. It has been proposed in the past to use fluorocarbon gases as precursors for the FIB milling of dielectrics. Preliminary experimental evaluation of Trifluoroacetic (Perfluoroacetic) Acid (TFA, CF3COOH) as a possible etching precursor for the HAR via milling in the application to FIB modification of ICs demonstrated that highly enhanced anisotropic milling of SiO2 in HAR vias is possible. A via with 9:1 aspect ratio was milled with accurate endpoint on Si and without apparent damage to the underlying Si substrate.

Focused Ion Beam: Advanced Technique for Device Modification

1994 ◽  
Vol 337 ◽  
Author(s):  
Marsha Abramo ◽  
Loren Hahn
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Materials ◽  
Advanced Technique ◽  
Aspect Ratios ◽  
Chip Technology ◽  
Design Changes ◽  
Critical Feedback

ABSTRACTFocused ion beam (FIB) technology is used to modify circuits for early-product design debug; it also has the capability to create probe points to underlying metallurgy, allowing device characterization while maintaining full functionality. These techniques provide critical feedback to designers for rapid verification of proposed design changes.Current FIB technology has its limitations because of redeposition of sputtered material; this phenomena may induce vertical electrical shorts and limit the achievable aspect ratio of a milled via to 6:1. Therefore, innovative enhancements are required to provide modification capability on planar chip technology which may utilize up to five levels of metallurgy. The ability to achieve high-aspect-ratio milling is required to access underlying circuitry. Vias with aspect ratios of 10:1 are necessary in some cases.This paper reviews a gas-assisted etching (GAE) process that enhances FIB milling by volatilizing the sputtered material, examines the results obtained from utilizing the GAE process for high-aspect-ratio milling, and discusses selectivity of semiconductor materials (silicon, aluminum, tungsten and silicon dioxide).

Effects of Variable Viscosity and Thermal Conductivity of CuO-Water Nanofluid on Heat Transfer Enhancement in Natural Convection: Mathematical Model and Simulation

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Eiyad Abu-Nada
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Variable Viscosity ◽  
Cylinder Surface ◽  
Transfer Enhancement

Heat transfer enhancement in horizontal annuli using variable thermal conductivity and variable viscosity of CuO-water nanofluid is investigated numerically. The base case of simulation used thermal conductivity and viscosity data that consider temperature property dependence and nanoparticle size. It was observed that for Ra≥104, the average Nusselt number was deteriorated by increasing the volume fraction of nanoparticles. However, for Ra=103, the average Nusselt number enhancement depends on aspect ratio of the annulus as well as volume fraction of nanoparticles. Also, for Ra=103, the average Nusselt number was less sensitive to volume fraction of nanoparticles at high aspect ratio and the average Nusselt number increased by increasing the volume fraction of nanoaprticles for aspect ratios ≤0.4. For Ra≥104, the Nusselt number was deteriorated everywhere around the cylinder surface especially at high aspect ratio. However, this reduction is only restricted to certain regions around the cylinder surface for Ra=103. For Ra≥104, the Maxwell–Garnett and the Chon et al. conductivity models demonstrated similar results. But, there was a deviation in the prediction at Ra=103 and this deviation becomes more significant at high volume fraction of nanoparticles. The Nguyen et al. data and the Brinkman model give completely different predictions for Ra≥104, where the difference in prediction of the Nusselt number reached 50%. However, this difference was less than 10% at Ra=103.

Sign in / Sign up

Export Citation Format

Share Document