This document discusses different methods for fabricating carbon nanotube (CNT) interconnects and comparing their performance. It proposes a double layer CNT interconnect structure that includes two CNT networks separated by a 1nm aluminum oxide layer. Testing shows that double layer structures have higher conductivity, less variation in conductance, and higher probabilities of conductive paths compared to single layer structures. The additional aluminum oxide layer is believed to help capture more CNTs during coating, allowing more tunneling pathways between the two CNT networks to improve conductivity. Phase transition phenomena in conductance based on size and structure are also investigated using percolation theory.
1) The document describes a study investigating the size-dependent conductivity of carbon nanotube (CNT) interconnects formed through a simple, low-temperature fabrication process involving slow spin coating and dry etching.
2) Two sets of CNT interconnects with varying widths and lengths were fabricated to characterize how conductivity is affected by the size of the interconnect regimes.
3) The results show that increasing the amount of CNT solution used in spin coating or the area of the CNT interconnect regime improves conductance by providing more conductive pathways through the random CNT networks. Conductivity transitions between different scaling behaviors could be explained by percolation theory.
This document discusses research into developing monolithically integrated cadmium telluride (CdTe) solar cell devices deposited via atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). The research aims to improve the fabrication process and efficiency of CdTe modules. Key steps studied include AP-MOCVD deposition of CdZnS/CdTe layers, addition of back contacts via thermal evaporation or screen printing, monolithic integration via mechanical scribing, and characterization of solar cell performance. Issues addressed include delamination, improving scribing precision, and damage to scribing tips. The goal is to advance the process from single solar cells to interconnected photovoltaic modules.
This document describes a novel multilayer fabrication process for superconducting electronics with customizable number of planarized superconducting layers. Key points:
- The process adds underground superconducting wiring layers below the ground plane of an existing 4-layer process, extending it to 12 layers total.
- An aluminum etch stop was previously used to define stackable vias but proved unreliable at larger scales. The new process defines vias without aluminum to improve yield.
- Diagnostic chips with test structures like Josephson junction arrays, inductors, and digital circuits were fabricated using the new 6-layer process and evaluated to characterize process quality and uniformity.
CNTFET Based Analog and Digital Circuit Designing: A ReviewIJMERJOURNAL
ABSTRACT: Silicon has been a material of choice for the last many decades and more than 95% of electronics devices are from silicon. However, silicon has reached to its saturation level and extracting more and more performance is difficult and costly now. A new material which has a potential to replace Si and can extend the scalability of devices below 22 nm is the carbon nanotube (CNT). CNT is a wonderful material possesses unique properties that make it a promising future material. CNT based field effect transistor (Cntfet) is a promising basic building block to complement the existing silicon based MOSFET and can result in the extension of the validity of Moore's law further. CNTFT has been used extensively in realizing electronics circuits. This paper presents the state of the art literature related to carbon nanotubes, carbon nanotube field effect transistors and CNTFET based circuit designing. A review of Cntfet based analog and digital circuits has been presented. It has been observed that the use of CNTFET has improved the performance of both analog and digital circuits. The work will be very useful to the people working in the field of CNT based analog and digital circuit designing.
The document discusses carbon nanotube (CNT)/epoxy matrix nanocomposites. It notes that dispersing CNTs homogeneously in the epoxy matrix is important to exploit their potential but is difficult due to aggregation. Methods to improve dispersion include using surfactants or functionalizing CNTs. Functionalization can degrade CNT properties so alternative methods are sought. The properties of CNT/epoxy nanocomposites depend on the degree of CNT dispersion, with higher conductivity achieved above the percolation threshold.
The development of desalination technology become a necessary due to the intense shortage of fresh water, especially in the gulf.
In the last six decades, the number of desalination units have increased dramatically.
Different techniques have been used for water desalination systems such as:
Capacitive deionization (CDI)
Multi-stage flash (MSF) distillation
Reverse osmosis (RO)
Electrodialysis
Nuclear power
CNT in nanocomposites and structural compositeslmezzo
The document discusses the development of carbon nano tubes (CNTs) in nanocomposites and structural composites. It describes three generations of CNT composites with CNTs arranged randomly, confined, or oriented. The first generation provided benefits like higher cleanliness and dimensional stability. Subsequent generations improved CNT-matrix interactions, dispersion, and the final targeted properties. The highest challenge is achieving the desired CNT dispersion and orientation cost-effectively to supply the market.
1) The document describes a study investigating the size-dependent conductivity of carbon nanotube (CNT) interconnects formed through a simple, low-temperature fabrication process involving slow spin coating and dry etching.
2) Two sets of CNT interconnects with varying widths and lengths were fabricated to characterize how conductivity is affected by the size of the interconnect regimes.
3) The results show that increasing the amount of CNT solution used in spin coating or the area of the CNT interconnect regime improves conductance by providing more conductive pathways through the random CNT networks. Conductivity transitions between different scaling behaviors could be explained by percolation theory.
This document discusses research into developing monolithically integrated cadmium telluride (CdTe) solar cell devices deposited via atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). The research aims to improve the fabrication process and efficiency of CdTe modules. Key steps studied include AP-MOCVD deposition of CdZnS/CdTe layers, addition of back contacts via thermal evaporation or screen printing, monolithic integration via mechanical scribing, and characterization of solar cell performance. Issues addressed include delamination, improving scribing precision, and damage to scribing tips. The goal is to advance the process from single solar cells to interconnected photovoltaic modules.
This document describes a novel multilayer fabrication process for superconducting electronics with customizable number of planarized superconducting layers. Key points:
- The process adds underground superconducting wiring layers below the ground plane of an existing 4-layer process, extending it to 12 layers total.
- An aluminum etch stop was previously used to define stackable vias but proved unreliable at larger scales. The new process defines vias without aluminum to improve yield.
- Diagnostic chips with test structures like Josephson junction arrays, inductors, and digital circuits were fabricated using the new 6-layer process and evaluated to characterize process quality and uniformity.
CNTFET Based Analog and Digital Circuit Designing: A ReviewIJMERJOURNAL
ABSTRACT: Silicon has been a material of choice for the last many decades and more than 95% of electronics devices are from silicon. However, silicon has reached to its saturation level and extracting more and more performance is difficult and costly now. A new material which has a potential to replace Si and can extend the scalability of devices below 22 nm is the carbon nanotube (CNT). CNT is a wonderful material possesses unique properties that make it a promising future material. CNT based field effect transistor (Cntfet) is a promising basic building block to complement the existing silicon based MOSFET and can result in the extension of the validity of Moore's law further. CNTFT has been used extensively in realizing electronics circuits. This paper presents the state of the art literature related to carbon nanotubes, carbon nanotube field effect transistors and CNTFET based circuit designing. A review of Cntfet based analog and digital circuits has been presented. It has been observed that the use of CNTFET has improved the performance of both analog and digital circuits. The work will be very useful to the people working in the field of CNT based analog and digital circuit designing.
The document discusses carbon nanotube (CNT)/epoxy matrix nanocomposites. It notes that dispersing CNTs homogeneously in the epoxy matrix is important to exploit their potential but is difficult due to aggregation. Methods to improve dispersion include using surfactants or functionalizing CNTs. Functionalization can degrade CNT properties so alternative methods are sought. The properties of CNT/epoxy nanocomposites depend on the degree of CNT dispersion, with higher conductivity achieved above the percolation threshold.
The development of desalination technology become a necessary due to the intense shortage of fresh water, especially in the gulf.
In the last six decades, the number of desalination units have increased dramatically.
Different techniques have been used for water desalination systems such as:
Capacitive deionization (CDI)
Multi-stage flash (MSF) distillation
Reverse osmosis (RO)
Electrodialysis
Nuclear power
CNT in nanocomposites and structural compositeslmezzo
The document discusses the development of carbon nano tubes (CNTs) in nanocomposites and structural composites. It describes three generations of CNT composites with CNTs arranged randomly, confined, or oriented. The first generation provided benefits like higher cleanliness and dimensional stability. Subsequent generations improved CNT-matrix interactions, dispersion, and the final targeted properties. The highest challenge is achieving the desired CNT dispersion and orientation cost-effectively to supply the market.
Carbon nanotubes (cnt) as interconnects for futureHarish Peta
The document analyzes carbon nanotubes (CNTs) as potential replacements for copper interconnects in future VLSI technology. It discusses the types of CNTs and analyzes mixed bundles of CNTs, comparing their resistance and capacitance to copper interconnects at local, intermediate, and global levels. CNT bundles have smaller resistance than copper for intermediate and global interconnects but higher resistance for local interconnects. The resistance of CNT bundles can be optimized by varying tube diameter and bundle density. CNT bundle capacitances are also marginally smaller than copper at all levels.
Mechanical behaviour of cement mortar & concrete for application of nano ...Mainak Ghosal
The document discusses research on improving cement and concrete properties through the addition of nano-materials like nano-silica, carbon nanotubes, and titanium dioxide. Testing of cement mortar cubes and M40 grade concrete found that the addition of 0.75% nano-silica increased the 28-day compressive strength of mortar by 32.55% while 0.02% carbon nanotubes increased the strength of concrete by 36% at 28 days. The optimum dosages identified through mortar testing - 0.75% nano-silica, 0.02% carbon nanotubes, and 1% titanium dioxide - also improved the strengths of concrete mixtures. Further microstructural characterization is needed to better understand the
Carbon nanotubes and their economic feasibilityJeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how the economic feasibility of carbon nanotubes is becoming better through the emergence of new forms of carbon nanotubes, new methods of synthesis, and the increased scale of production equipment. New forms of carbon nanotubes continue to be developed; new ones include carbon nanobuds, doped carbon nanotubes, and graphenated carbon nanotubes, each of which includes many variations. The large number of variations suggests that carbon nanotubes will likely experience improvements in performance and the number of applications will continue to grow.
This document discusses electrospun carbon nanofibers. It begins by noting the interest in carbon nanofibers due to their potential applications and describes typical production methods. It then explains that carbon nanofibers can be produced through pyrolyzing electrospun polymer nanofibers. The document goes on to describe the specific electrospinning process used, utilizing polyacrylonitrile dissolved in dimethylformamide and optimizing the oxidation and carbonization processes to produce carbon nanofibers in the hundreds of nanometers in diameter. The carbon nanofibers were then analyzed using scanning electron microscopy and infrared spectroscopy.
This presentation provides information on carbon nanotubes and their properties and applications. It discusses different types of carbon nanotubes including single-wall nanotubes, multi-wall nanotubes, Buckminsterfullerene, and C70 fullerene. Methods for characterizing carbon nanotubes are also covered, such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. A wide range of potential applications for carbon nanotubes are presented, such as in conductive materials, composites, filtration, biomedical uses, electronics, and more.
Shulze - Surface and Thin Film Characterization of Superconducting Multilayer...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Surface and Thin Film Characterization of Superconducting Multilayer films for application in RF (Roland Schulze - 30')
Speaker: Roland Schulze - Los Alamos National Laboratory | Duration: 30 min.
Abstract
The use of multilayer ultra-thin films on the interior surfaces of Nb superconducting RF cavities shows great promise in substantially improving the performance characteristics of superconducting RF cavities into the 100 MV/m range by increasing the RF critical magnetic field, HRF, through careful choice of new materials and thin film structures. However, there are substantial materials science challenges associated with producing such complex film structures, particularly for conformal application of uniform thin films on the interior surfaces of RF cavities. Here we present surface and thin film analysis of ultra-thin films of two candidate materials, MgB2 and NbN superconductors, deposited through several different methods, along with multilayers produced with alternating superconductor and dielectric films. We report on the analysis methods and techniques, using primarily x-ray photoelectron spectroscopy and Auger spectroscopy with ion sputter depth profiling, and describe results from variety of thin film samples. The materials stability, microstructure, chemistry, and thin film morphology are highly dependent on methods and parameters used in the thin film deposition. From our analysis, important factors for producing quality superconducting and dielectric films include chemical stoichiometry, impurity content, deposition temperature, substrate choice and conditioning, choice of dielectric material, and the nature of the thin film interfaces. These factors will be discussed in the context of the production methods used for these ultra-thin superconducting films.
This document provides an overview of carbon nanotubes. It discusses the history of carbon nanotube discovery from the 1950s to 1991. It describes what carbon nanotubes are, which are tube-shaped materials made of carbon that have diameters on the nanometer scale. The document classifies carbon nanotubes based on chirality, layers, and conductivity. It outlines the properties of carbon nanotubes including their small size, strength, flexibility, and thermal and electrical conductivity. Methods for synthesizing carbon nanotubes are described, including arc discharge, laser ablation, and chemical vapor deposition. Applications of carbon nanotubes discussed include use in energy storage, molecular electronics, sensors, composites, and desalination
Carbon nanotube fibers (CNTFs) were synthesized using a horizontally spinning chemical vapor deposition (CVD) technique. Scanning electron microscopy (SEM) was used to characterize the microstructure of the CNTFs. The CNTFs were grown using thermal CVD with iron catalyst and methane carbon source. During growth, the CNTs were directly pulled and twisted to form fibers. SEM analysis was conducted to investigate the morphology, shape, and other properties of the CNTFs, including electrical conductivity. This technique aims to develop high performance EM transmitter materials using CNTFs.
CARBON NANOTUBES-TREATMENT AND FUNCTIONALIZATIONArjun K Gopi
Carbon nanotubes are fullerene-related structures consisting of graphene cylinders closed at either end with pentagonal rings. There are two main types: single-walled nanotubes (SWNTs), which have diameters around 1 nanometer, and multi-walled nanotubes (MWNTs) made of multiple concentric graphene cylinders. Functionalization of carbon nanotubes is important for applications and can occur through non-covalent interactions like wrapping of surfactants or polymers or through covalent bonding by attaching molecules to existing defects or through reactions to functionalize the graphene sidewalls. The document discusses different methods of non-covalent and covalent functionalization of carbon nanotubes.
A study of Carbon Nanotubes as Smart Reinforcemants for Glass/ Glass ceramic ...Rahul Dubey
This document presents a study on carbon nanotubes (CNTs) as reinforcements for glass and glass ceramic matrix composites. CNTs have excellent mechanical and physical properties due to their nano-scale size. The document discusses methods of CNT production, their properties, and manufacturing of CNT-reinforced glass composites. Incorporating CNTs improves the mechanical, electrical and thermal properties of the brittle glass matrix. Potential applications include structural components, heat sinks, and thermal barrier coatings. However, more research is still needed to fully understand CNT reinforcement effects and address issues like mass production costs and health impacts.
This document discusses carbon nanotube field-effect transistors (CNTFETs) as a potential substitute for MOSFETs. CNTFETs could help overcome limitations of MOSFET scaling by providing higher carrier mobility, excellent electrostatics, and gate control. CNTFETs exhibit advantages like better threshold voltage and subthreshold slope control as well as higher current density and transconductance compared to MOSFETs. However, mass production of CNTFETs faces challenges related to defects, failure rates, and production costs that are higher than for traditional CMOS.
Carbon exists in several allotropes including diamond, graphite, fullerenes, and carbon nanotubes. Fullerenes are hollow spherical or cylindrical molecules made entirely of carbon atoms arranged in hexagonal and pentagonal rings. Carbon nanotubes are cylindrical tubes composed of graphene sheets that are rolled up, and can be single-walled or multi-walled depending on the number of concentric tubes. Carbon nanotubes have extraordinary mechanical, electrical, and thermal properties that make them useful for applications such as conductive composites, energy storage, field emission displays, and reinforced materials many times stronger than steel.
Graphene and hexagonal boron nitride filled epoxy nanocompositesArun Yadav
The document describes a two-stage project to develop polymer nanocomposites with improved thermal conductivity for electronic packaging applications. The first stage involves establishing a high concentration dispersion of hexagonal boron nitride and graphene using a suitable surfactant. The second stage uses this dispersion to prepare epoxy nanocomposites. The nanocomposites will be characterized using techniques like UV-Vis-NIR spectroscopy, FTIR spectroscopy, SEM and TEM to analyze properties. The goal is to create graphene and boron nitride filled polymer composites with higher thermal conductivity.
Carbon nanotubes with special application to the cnt reoinforced glass and glassRahul Dubey
The document discusses carbon nanotubes (CNTs), their properties, production methods, and applications. Specifically, it focuses on using CNTs to reinforce glass and glass-ceramic matrix composites. The key points are:
1) CNTs have excellent mechanical and thermal properties that make them promising reinforcements. Their production via electric arc discharge, laser ablation, or chemical vapor deposition controls their quality.
2) Manufacturing CNT-reinforced glass/glass-ceramic composites requires well-dispersed CNTs, strong interfaces, and consolidation to high densities using techniques like spark plasma sintering.
3) Preliminary results show the composites have improved hardness, elastic modulus
This document summarizes research on using laser processing techniques to deposit nanocrystalline titanium dioxide (nc-TiO2) films for use in dye-sensitized solar cells. Pulsed laser deposition was used to deposit a dense TiO2 layer and laser direct-write was used to deposit porous nc-TiO2 layers of varying thickness. Solar cells made with laser-processed nc-TiO2 layers showed a power conversion efficiency of up to 4.3% under solar illumination. Thicker nc-TiO2 layers increased short circuit current but decreased open circuit voltage, due to increased recombination losses. Laser processing techniques allow conformal deposition of nc-TiO2 without masks or additional patterning steps.
Carbon nanotubes for Aerospace applicationsnasreenhabeeb
1. The document discusses using single-walled carbon nanotube (SWCNT) composites with epoxy to create structural and conductive aerospace adhesives.
2. It presents the need for such adhesives to provide both structural bonding and electrical conductivity as alternatives to riveting.
3. The document describes creating SWCNT-epoxy composites with 0.2-1wt% SWCNT loading and evaluating their mechanical properties, electrical conductivity, and performance in lap shear and peel tests. It found 0.5wt% provided electrical conductivity without reducing mechanical properties.
This document discusses using inkjet printing to pattern carbon nanotubes (CNTs) for multifunctional composite applications. It explores how to functionalize CNTs through oxidation to improve compatibility with polymer matrices. The objectives are to examine how the electrical conductivity of printed CNT networks is influenced by printing parameters and surface functionalization. An inkjet printing process is used to deposit CNT solutions onto fiber substrates with high precision. The conductivity is characterized for different printing configurations and levels of CNT sheet oxidation. The results show that printing direction, droplet spacing, and repeated overwriting influence conductivity, and that surface functionalization through ozone oxidation can both increase and decrease conductivity depending on exposure time.
This document discusses perovskite solar cells. It begins with an overview of different photovoltaic technologies and efficiency charts. It then discusses the properties of perovskite materials and various device architectures for perovskite solar cells. The document outlines fabrication methods for perovskite solar cells, including potential replacements for lead and printed or roll-to-roll approaches. It concludes with a discussion of the commercialization potential and future outlook of perovskite solar cells.
Fabrication and Mechanical Charecterization of Cnt NanocompositesIOSR Journals
This document discusses the fabrication and mechanical characterization of carbon nanotube (CNT) nanocomposites. Multi-walled carbon nanotubes were functionalized with amine and epoxide groups and then mixed with epoxy resin to create nanocomposites at various CNT loadings. The mechanical properties of the nanocomposites, including flexural strength, flexural modulus, and interlaminar shear strength, were tested and compared to a control composite without CNTs. Fourier transform infrared spectroscopy was used to confirm the functionalization of the CNTs. The results showed that amine-functionalized CNT composites generally had better mechanical properties than epoxide-functionalized or
This document summarizes an investigation into fabricating and evaluating carbon nanotube (CNT) interconnects using a spin coating technique. The researchers found that CNT interconnects fabricated using a slow spin coating rate had higher conductivity (>102 S/cm) and conductive probability (around 30%) compared to a normal spin coating rate. Inserting metal bridges into 1000-micron long CNT interconnects was also found to improve performance. Statistical analysis of the CNT interconnect characteristics showed they followed a power law relationship with CNT density, indicating the formation of conductive CNT networks.
A carbon nanotube field-effect transistor (CNTFET) uses a carbon nanotube as the channel material instead of silicon. Early CNTFETs used a back-gate design with random nanotube placement, while improved top-gated and wrap-around gate designs provide better control over the channel and higher performance. CNTFETs offer advantages like high electron mobility, current density, and transconductance compared to MOSFETs due to carbon nanotubes' unique electronic properties.
Carbon nanotubes (cnt) as interconnects for futureHarish Peta
The document analyzes carbon nanotubes (CNTs) as potential replacements for copper interconnects in future VLSI technology. It discusses the types of CNTs and analyzes mixed bundles of CNTs, comparing their resistance and capacitance to copper interconnects at local, intermediate, and global levels. CNT bundles have smaller resistance than copper for intermediate and global interconnects but higher resistance for local interconnects. The resistance of CNT bundles can be optimized by varying tube diameter and bundle density. CNT bundle capacitances are also marginally smaller than copper at all levels.
Mechanical behaviour of cement mortar & concrete for application of nano ...Mainak Ghosal
The document discusses research on improving cement and concrete properties through the addition of nano-materials like nano-silica, carbon nanotubes, and titanium dioxide. Testing of cement mortar cubes and M40 grade concrete found that the addition of 0.75% nano-silica increased the 28-day compressive strength of mortar by 32.55% while 0.02% carbon nanotubes increased the strength of concrete by 36% at 28 days. The optimum dosages identified through mortar testing - 0.75% nano-silica, 0.02% carbon nanotubes, and 1% titanium dioxide - also improved the strengths of concrete mixtures. Further microstructural characterization is needed to better understand the
Carbon nanotubes and their economic feasibilityJeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how the economic feasibility of carbon nanotubes is becoming better through the emergence of new forms of carbon nanotubes, new methods of synthesis, and the increased scale of production equipment. New forms of carbon nanotubes continue to be developed; new ones include carbon nanobuds, doped carbon nanotubes, and graphenated carbon nanotubes, each of which includes many variations. The large number of variations suggests that carbon nanotubes will likely experience improvements in performance and the number of applications will continue to grow.
This document discusses electrospun carbon nanofibers. It begins by noting the interest in carbon nanofibers due to their potential applications and describes typical production methods. It then explains that carbon nanofibers can be produced through pyrolyzing electrospun polymer nanofibers. The document goes on to describe the specific electrospinning process used, utilizing polyacrylonitrile dissolved in dimethylformamide and optimizing the oxidation and carbonization processes to produce carbon nanofibers in the hundreds of nanometers in diameter. The carbon nanofibers were then analyzed using scanning electron microscopy and infrared spectroscopy.
This presentation provides information on carbon nanotubes and their properties and applications. It discusses different types of carbon nanotubes including single-wall nanotubes, multi-wall nanotubes, Buckminsterfullerene, and C70 fullerene. Methods for characterizing carbon nanotubes are also covered, such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. A wide range of potential applications for carbon nanotubes are presented, such as in conductive materials, composites, filtration, biomedical uses, electronics, and more.
Shulze - Surface and Thin Film Characterization of Superconducting Multilayer...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Surface and Thin Film Characterization of Superconducting Multilayer films for application in RF (Roland Schulze - 30')
Speaker: Roland Schulze - Los Alamos National Laboratory | Duration: 30 min.
Abstract
The use of multilayer ultra-thin films on the interior surfaces of Nb superconducting RF cavities shows great promise in substantially improving the performance characteristics of superconducting RF cavities into the 100 MV/m range by increasing the RF critical magnetic field, HRF, through careful choice of new materials and thin film structures. However, there are substantial materials science challenges associated with producing such complex film structures, particularly for conformal application of uniform thin films on the interior surfaces of RF cavities. Here we present surface and thin film analysis of ultra-thin films of two candidate materials, MgB2 and NbN superconductors, deposited through several different methods, along with multilayers produced with alternating superconductor and dielectric films. We report on the analysis methods and techniques, using primarily x-ray photoelectron spectroscopy and Auger spectroscopy with ion sputter depth profiling, and describe results from variety of thin film samples. The materials stability, microstructure, chemistry, and thin film morphology are highly dependent on methods and parameters used in the thin film deposition. From our analysis, important factors for producing quality superconducting and dielectric films include chemical stoichiometry, impurity content, deposition temperature, substrate choice and conditioning, choice of dielectric material, and the nature of the thin film interfaces. These factors will be discussed in the context of the production methods used for these ultra-thin superconducting films.
This document provides an overview of carbon nanotubes. It discusses the history of carbon nanotube discovery from the 1950s to 1991. It describes what carbon nanotubes are, which are tube-shaped materials made of carbon that have diameters on the nanometer scale. The document classifies carbon nanotubes based on chirality, layers, and conductivity. It outlines the properties of carbon nanotubes including their small size, strength, flexibility, and thermal and electrical conductivity. Methods for synthesizing carbon nanotubes are described, including arc discharge, laser ablation, and chemical vapor deposition. Applications of carbon nanotubes discussed include use in energy storage, molecular electronics, sensors, composites, and desalination
Carbon nanotube fibers (CNTFs) were synthesized using a horizontally spinning chemical vapor deposition (CVD) technique. Scanning electron microscopy (SEM) was used to characterize the microstructure of the CNTFs. The CNTFs were grown using thermal CVD with iron catalyst and methane carbon source. During growth, the CNTs were directly pulled and twisted to form fibers. SEM analysis was conducted to investigate the morphology, shape, and other properties of the CNTFs, including electrical conductivity. This technique aims to develop high performance EM transmitter materials using CNTFs.
CARBON NANOTUBES-TREATMENT AND FUNCTIONALIZATIONArjun K Gopi
Carbon nanotubes are fullerene-related structures consisting of graphene cylinders closed at either end with pentagonal rings. There are two main types: single-walled nanotubes (SWNTs), which have diameters around 1 nanometer, and multi-walled nanotubes (MWNTs) made of multiple concentric graphene cylinders. Functionalization of carbon nanotubes is important for applications and can occur through non-covalent interactions like wrapping of surfactants or polymers or through covalent bonding by attaching molecules to existing defects or through reactions to functionalize the graphene sidewalls. The document discusses different methods of non-covalent and covalent functionalization of carbon nanotubes.
A study of Carbon Nanotubes as Smart Reinforcemants for Glass/ Glass ceramic ...Rahul Dubey
This document presents a study on carbon nanotubes (CNTs) as reinforcements for glass and glass ceramic matrix composites. CNTs have excellent mechanical and physical properties due to their nano-scale size. The document discusses methods of CNT production, their properties, and manufacturing of CNT-reinforced glass composites. Incorporating CNTs improves the mechanical, electrical and thermal properties of the brittle glass matrix. Potential applications include structural components, heat sinks, and thermal barrier coatings. However, more research is still needed to fully understand CNT reinforcement effects and address issues like mass production costs and health impacts.
This document discusses carbon nanotube field-effect transistors (CNTFETs) as a potential substitute for MOSFETs. CNTFETs could help overcome limitations of MOSFET scaling by providing higher carrier mobility, excellent electrostatics, and gate control. CNTFETs exhibit advantages like better threshold voltage and subthreshold slope control as well as higher current density and transconductance compared to MOSFETs. However, mass production of CNTFETs faces challenges related to defects, failure rates, and production costs that are higher than for traditional CMOS.
Carbon exists in several allotropes including diamond, graphite, fullerenes, and carbon nanotubes. Fullerenes are hollow spherical or cylindrical molecules made entirely of carbon atoms arranged in hexagonal and pentagonal rings. Carbon nanotubes are cylindrical tubes composed of graphene sheets that are rolled up, and can be single-walled or multi-walled depending on the number of concentric tubes. Carbon nanotubes have extraordinary mechanical, electrical, and thermal properties that make them useful for applications such as conductive composites, energy storage, field emission displays, and reinforced materials many times stronger than steel.
Graphene and hexagonal boron nitride filled epoxy nanocompositesArun Yadav
The document describes a two-stage project to develop polymer nanocomposites with improved thermal conductivity for electronic packaging applications. The first stage involves establishing a high concentration dispersion of hexagonal boron nitride and graphene using a suitable surfactant. The second stage uses this dispersion to prepare epoxy nanocomposites. The nanocomposites will be characterized using techniques like UV-Vis-NIR spectroscopy, FTIR spectroscopy, SEM and TEM to analyze properties. The goal is to create graphene and boron nitride filled polymer composites with higher thermal conductivity.
Carbon nanotubes with special application to the cnt reoinforced glass and glassRahul Dubey
The document discusses carbon nanotubes (CNTs), their properties, production methods, and applications. Specifically, it focuses on using CNTs to reinforce glass and glass-ceramic matrix composites. The key points are:
1) CNTs have excellent mechanical and thermal properties that make them promising reinforcements. Their production via electric arc discharge, laser ablation, or chemical vapor deposition controls their quality.
2) Manufacturing CNT-reinforced glass/glass-ceramic composites requires well-dispersed CNTs, strong interfaces, and consolidation to high densities using techniques like spark plasma sintering.
3) Preliminary results show the composites have improved hardness, elastic modulus
This document summarizes research on using laser processing techniques to deposit nanocrystalline titanium dioxide (nc-TiO2) films for use in dye-sensitized solar cells. Pulsed laser deposition was used to deposit a dense TiO2 layer and laser direct-write was used to deposit porous nc-TiO2 layers of varying thickness. Solar cells made with laser-processed nc-TiO2 layers showed a power conversion efficiency of up to 4.3% under solar illumination. Thicker nc-TiO2 layers increased short circuit current but decreased open circuit voltage, due to increased recombination losses. Laser processing techniques allow conformal deposition of nc-TiO2 without masks or additional patterning steps.
Carbon nanotubes for Aerospace applicationsnasreenhabeeb
1. The document discusses using single-walled carbon nanotube (SWCNT) composites with epoxy to create structural and conductive aerospace adhesives.
2. It presents the need for such adhesives to provide both structural bonding and electrical conductivity as alternatives to riveting.
3. The document describes creating SWCNT-epoxy composites with 0.2-1wt% SWCNT loading and evaluating their mechanical properties, electrical conductivity, and performance in lap shear and peel tests. It found 0.5wt% provided electrical conductivity without reducing mechanical properties.
This document discusses using inkjet printing to pattern carbon nanotubes (CNTs) for multifunctional composite applications. It explores how to functionalize CNTs through oxidation to improve compatibility with polymer matrices. The objectives are to examine how the electrical conductivity of printed CNT networks is influenced by printing parameters and surface functionalization. An inkjet printing process is used to deposit CNT solutions onto fiber substrates with high precision. The conductivity is characterized for different printing configurations and levels of CNT sheet oxidation. The results show that printing direction, droplet spacing, and repeated overwriting influence conductivity, and that surface functionalization through ozone oxidation can both increase and decrease conductivity depending on exposure time.
This document discusses perovskite solar cells. It begins with an overview of different photovoltaic technologies and efficiency charts. It then discusses the properties of perovskite materials and various device architectures for perovskite solar cells. The document outlines fabrication methods for perovskite solar cells, including potential replacements for lead and printed or roll-to-roll approaches. It concludes with a discussion of the commercialization potential and future outlook of perovskite solar cells.
Fabrication and Mechanical Charecterization of Cnt NanocompositesIOSR Journals
This document discusses the fabrication and mechanical characterization of carbon nanotube (CNT) nanocomposites. Multi-walled carbon nanotubes were functionalized with amine and epoxide groups and then mixed with epoxy resin to create nanocomposites at various CNT loadings. The mechanical properties of the nanocomposites, including flexural strength, flexural modulus, and interlaminar shear strength, were tested and compared to a control composite without CNTs. Fourier transform infrared spectroscopy was used to confirm the functionalization of the CNTs. The results showed that amine-functionalized CNT composites generally had better mechanical properties than epoxide-functionalized or
This document summarizes an investigation into fabricating and evaluating carbon nanotube (CNT) interconnects using a spin coating technique. The researchers found that CNT interconnects fabricated using a slow spin coating rate had higher conductivity (>102 S/cm) and conductive probability (around 30%) compared to a normal spin coating rate. Inserting metal bridges into 1000-micron long CNT interconnects was also found to improve performance. Statistical analysis of the CNT interconnect characteristics showed they followed a power law relationship with CNT density, indicating the formation of conductive CNT networks.
A carbon nanotube field-effect transistor (CNTFET) uses a carbon nanotube as the channel material instead of silicon. Early CNTFETs used a back-gate design with random nanotube placement, while improved top-gated and wrap-around gate designs provide better control over the channel and higher performance. CNTFETs offer advantages like high electron mobility, current density, and transconductance compared to MOSFETs due to carbon nanotubes' unique electronic properties.
Effect of Chirality and Oxide Thikness on the Performance of a Ballistic CNTF...IJECEIAES
Since the discovery of 1D nano-object, they are constantly revealing significant physical properties. In this regard, carbon nanotube (CNT) is considered as a promising candidate for application in future nanoelectronics devices like carbon nanotube field effect transistor (CNTFET). In this work, the impact of chirality and gate oxide thikness on the electrical characteristics of a CNTFET are studied. The chiralities used are (5, 0), (10, 0), (19, 0), (26, 0), and the gate oxide thikness varied from 1 to 5 nm. This work is based on a numerical simulation program based on surface potential model. CNTFET Modeling is useful for semiconductor industries for nano scale devices manufacturing. From our results we have observed that the output current increases with chirality increasing. We have also highlighted the importance of the gate oxide thickness on the drain current that increases when gate oxide is thin.
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Carbon nanotubes properties and applicationsAMIYA JANA
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A Comparative Performance Analysis of Copper on Chip and CNTFET Nano Intercon...IRJET Journal
This document compares the performance of copper and carbon nanotube (CNT) interconnects at the 32nm technology node. Simulation results show that CNT interconnects outperform copper interconnects in key metrics like leakage power. CNT interconnects exhibited 11% lower off-state current (IOFF) variation and reduced leakage power in benchmark circuits by up to 53% compared to copper. Overall, CNT interconnects coupled with CNTFET models were found to consume less energy, have lower transmission latency, and reduced leakage power as technology is scaled down compared to copper interconnects.
"A presentation on Carbon Nano-tubes"
List of Contents:
Introduction
Types and Classification of CNTs
Methods of Synthesis
Properties
Defects
Applications
Health Hazards
Pros and Cons
Scope
Conclusion
Created by:
Er. Ankit Chandan
ankit29chandan@gmail.com
https://www.facebook.com/ankit29chandan
Low Cost Synthesis of Single Walled Carbon Nanotubes from Coal Tar Using Arc ...IOSRJAP
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two modules, causing Sum and Cout signals are produced in a parallel manner. All inputs have been used
straight, without inverting. These designs also used the special feature of CNFET that is controlling the
threshold voltage by adjusting the diameters of CNFETs to achieve the best performance and right voltage
levels. All simulation performed using Synopsys HSPICE software and the proposed designs are compared
to other classical and modern CMOS and CNFET-based full adder cells in terms of delay, power
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Structure, chemical, and physical properties of Multiwalled Carbon Nanotubes (MWCNTs) after
modification by dielectric barrier discharge (DBD) at atmospheric pressure is investigated using
Transmission Electron Microscopy (TEM), Raman and Uv-vis-NIR spectroscopy. Effects of plasma
treatment time on MWCNTs are analyzed. TEM result shows that during the short period of plasma
treatment time of 5 minutes, the tube surface experienced a few damages. With increase in plasma
treatment time, the tube surface is damaged to a certain extent. Intensity ratio, ID/IG through Raman
analysis shows a good agreement with TEM. The values of ID/IG of the modified MWCNTs are larger than
those of pristine MWCNTs. An increase of ID/IG indicates that considerable defects are produced on the
surfaces of MWCNTs. The treated MWCNTs has energy band gap compared to zero band gap of
untreated MWCNTs. It is believed that the defect site of MWCNTs can modify the electronics properties of
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This document summarizes a study investigating the effects of morphology and pore size distribution on the physicochemical properties of graphite nanosheets/nanoporous carbon black/cerium oxide nanoparticle electrodes for electrochemical capacitors. Electrodes with different compositions of these materials were fabricated and their surfaces and pores were characterized using SEM. Electrochemical testing showed that electrodes with a mixture of materials exhibited the highest capacitance due to having macro, micro, and nano pores that increased the accessible surface area. Introducing cerium oxide nanoparticles created micro pores, while carbon black particles created macro pores and rearranged the graphite nanosheets. This nanoporous structure resulted in an electrode with the highest capacitance of 16.2 F/
Injection-Molded Parts of Polypropylene/Multi-WallJosé Luis Feijoo
Polypropylene-based composites filled with multi-wall
carbon nanotubes (MWCNTs), ranging from 1 to 6
wt%, were obtained by injection molding from a previous
masterbatch compounded by twin-screw extrusion
(TSE). Resultant electrical percolation phenomenon
was related to the ultrathin structure of the carbonbased
fillers and the high dispersion achieved in the
thermoplastic matrix. In particular, conductivity experiments
showed a threshold value of 3 wt% (1.3 vol%) of
MWCNTs for percolation to occur. Electrical percolation
was achieved as a result of the formation of an
interconnected three-dimensional structure compromising
a top average inter-nanotube distance of about
493 nm among isolated nanotubes in polypropylene.
The current work is hoped to bear significance toward
understanding of the electrical performance for industrial
ultrathin carbon black-based polyolefin composites.
Carbon Nanotube Based Circuit Designing: A ReviewIJERDJOURNAL
ABSTRACT:- A new material and its associated device which have potential to replace Si and CMOS and can extend the scalability of devices below 22 nm is the carbon nanotube (CNT) and its associated transistor, the carbon nanotube field effect transistor (CNTFET). CNT possesses unique properties that make it a promising future material. Similarly, CNTFET is a promising basic building block to complement the existing silicon based MOSFET and can result in the extension of the validity of Moore's law further. This paper presents the state of the art literature related to carbon nanotubes, carbon nanotube field effect transistors and CNTFET based circuit designing. A review of CNTFET based analog and digital circuits has been presented. It has been observed that the use of CNTFET can improve the performance of both analog and digital circuits. The work will be of utmost use to the people working in the field of CNT based analog and digital circuit designing.
International Journal of Engineering Research and DevelopmentIJERD Editor
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Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
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Marine and Agriculture engineering,
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International Journal of Engineering Research and Development
CNT(Microelectron. Reliab)2
1. High performance of CNT-interconnects by the multi-layer structure
Wei-Chih Chiu ⇑
, Bing-Yue Tsui
Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, No. 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan, ROC
a r t i c l e i n f o
Article history:
Received 28 October 2013
Received in revised form 5 December 2013
Accepted 26 December 2013
Available online xxxx
a b s t r a c t
In this work, we propose two carbon nanotube (CNT) network fabrication processes, the normal spin rate
coating (NR) and the slow spin rate coating (SR), and two interconnect structures, the single layer struc-
ture (SL) and the double layer structure (DL), to construct CNT-interconnects. We demonstrate and com-
pare the performance of the CNT-interconnects with four kinds of process combinations: NR/SL, NR/DL,
SR/SL and SR/DL. Generally, in the midst of these four combinations, the DL samples have higher conduc-
tive probabilities and less conductance variations, while SL/SR samples have the higher average conduc-
tance under the same amount of the CNT solution for CNT network formation. In addition, the phase
transition phenomena occurred in the size dependent average conductance of CNT-interconnects are
characterized and investigated by percolation theory. With the elongation of CNT-interconnects, the
relationships between the average conductance and the square number would shift from linear region,
power region to percolation region. Moreover, the results show that the resistance from the additional
layer of Al2O3 in the double layer interconnect structure would influence the phase transition in the
conductance of CNT-interconnects as well.
Ó 2013 Published by Elsevier Ltd.
1. Introduction
In the late 1990s, copper has been introduced into the inte-
grated circuit manufacturing as an interconnect material of prior-
ity with the feature sizes decreasing [1]. However, with the
continuous evolvement in the semiconductor technology, the
available interconnect fabrication process has no longer been suf-
ficient to keep abreast with the future CMOS technological gener-
ations. Constant scaling has been altering the electrical properties
of copper, such as the conductivity and reliability, due to the addi-
tional electron–surface scattering, grain boundary scattering and
surface roughness-induced scattering [2]. Besides, the fabrication
processes for copper deposition, patterning and a more applicable
barrier material to prevent the copper atoms from diffusing into
the surrounding insulator have also become critical issues for the
further development of the Cu-interconnects [3]. Therefore, new
interconnect technology with high performance and easy fabrica-
tion processes has been greatly of concern for semiconductor
industries.
The carbon nanotube (CNT), first discovered by Iijima in 1991
[4], has aroused plenty of interest owing to the extraordinary phys-
ical properties [5–7], such as high current density enduring
ability (2.5 Â 109
A/cm2
) and extremely high carrier mobility
(2 Â 104
cm2
/V s) [8], and has quickly been adopted for a variety
of applications in these few years [9–11], particularly in the nano-
electronics area [12,13]. Although the tube-to-tube variations aris-
ing from non-idealities in the synthesis process have restricted the
application of the CNTs [14], it has been proved that such issue
could be effectively alleviated by the ensemble averaging over
large amount of CNTs [15]. In spite of the fact that the unsatisfac-
tory reliability still exists in CNT networks for now, but the nice
performance and simple fabrication processes still make CNT net-
works viewed as one of the most efficacious approaches to inte-
grating the CNTs into microelectronic fabrication.
Until now, several methods for the CNT network formation have
constantly been proposed. For instance, spin coating the CNT solu-
tion directly onto a wafer [16], filtering out the solvent by vacuum
filtration to deposit the CNTs on a substrate [17], transferring CNTs
to a flexible plastic substrate by printing methods [18], or growing
CNTs directly on dispersed catalysts by the CVD at temperatures
higher than 400 °C [19]. Among these fabrication processes, the
spin coating method possesses the merits of the most simplicity
and being able to exercise in a low temperature process.
In early 2013, we adopted the slow rate spin coating (SR) and
dry etching to fabricate CNT-interconnects in the single layer con-
figuration (SL) and enhanced the maximum average sheet conduc-
tance to approximately 10À4
S by a total amount of 20 mL CNT
solution [20]. However, due to the CNT synthesis process caused
variations, it is difficult to narrow the conductance variations while
simultaneously retain high conductive probabilities by such slow
rate spin coating. Generally, it is found that, in most cases, the
0026-2714/$ - see front matter Ó 2013 Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.microrel.2013.12.024
⇑ Corresponding author. Tel.: +886 6 2631802; fax: +886 3 5131570.
E-mail address: chiweich0327@gmail.com (W.-C. Chiu).
Microelectronics Reliability xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Microelectronics Reliability
journal homepage: www.elsevier.com/locate/microrel
Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
http://dx.doi.org/10.1016/j.microrel.2013.12.024
2. conductance of the CNT-interconnects fabricated by 20 mL amount
of the CNT solution has more than two orders of variations as
shown in Fig. 1(a) and (b). Besides, the conductive probabilities
of the long dimensional CNT-interconnects are quite low, such as
20% and 0% conductive probabilities of the CNT-interconnects with
100 and 200 square numbers, respectively, as demonstrated in
Fig. 1(b). This present paper first demonstrates the performance
of CNT-interconnects constructed by two kinds of spin coating
methods, normal rate or slow rate spin coating, and then patterned
by dry etching. Then, we will show that how the multi-layer inter-
connect structure improves the conductivity, the conductive prob-
ability and the conductance variation of CNT-interconnects. It is
proved that the double layer interconnect structure is effective to
reduce the conductance variations within almost one order,
improve the conductive probabilities of the long dimensional
CNT-interconnects and maintain the maximum average sheet con-
ductance about 5 Â 10À5
S at the same time. Finally, the phase
transition phenomena in the size and the interconnect structure
dependent CNT-interconnect electrical properties are included
and investigated by percolation theory as well.
2. CNT-interconnect fabrication
In this experiment, we used ‘‘square number’’ as a unit, the
length (L) divided by the width (W) of an interconnect, to charac-
terize each CNT-interconnect dimension and sorted them into
two series, the width varying series and the length varying series.
In the width varying series, the lengths of CNT-interconnects are
fixed at 100 lm and the widths range from 500 lm to 5 lm corre-
sponding to 0.2–20 in square numbers. On the other hand, in the
length varying series, the widths of CNT-interconnects are fixed
at 5 lm and the lengths range from 5 lm to 1000 lm correspond-
ing to 1–200 in square numbers. The detail geometries of the width
and the length varying series of CNT-interconnects adopted for this
work are listed in the insets of Fig. 1(a) and (b), respectively. More-
over, the precise gauge of individual CNT-interconnect conduc-
tance was done by a set of four-probe bridge resistors as
depicted in Fig. 1(c).
To begin with, a boron-doped (100)-oriented 4-inch-diameter
silicon wafer was first grown by a 200-nm-thick layer of thermal
oxide and then capped with a 1-nm-thick layer of Al2O3 which
was done by 250 cycles of atomic-layer deposition (ALD) with
the precursors, trimethylaluminum (TAM) and water, in the tem-
perature of 160 °C. The spin-coated CNT networks in our experi-
ments were formed by the AP-grade discharge grown CNTs with
the purity of 50–70% and residue catalysts of yttrium (Y) and nickel
(Ni). These rod-like CNTs have an average diameter of 1.4 nm and
an average length of 3.5 lm, and the ratio of the semiconducting
and the metallic CNT distribution is approximately 2:1 as deter-
mined by the Raman spectroscopy [21].
The solution for CNT network formation was prepared by dis-
solving 2 mg CNT powder into dimethylformamide (DMF) solvent
and then sonicating 24 h for uniform dispersion. There were two
kinds of processes for the CNT network formation in this experi-
ment, the normal rate spin coating (NR) and the slow rate spin
coating (SR). The former process used a spin speed of 500 rpm
for 30 s to coat the CNTs onto the wafer after 0.5 mL CNT solution
was dropped by a dropper at the center per cycle, while the latter
one lowered the spin speed to 100 rpm for 10 s per cycle [22]. In
both cases, a heating process was utilized for evaporating the sol-
vent out after each coating cycle. Then the sets of four-probe bridge
resistors for conductance measurement were fabricated by depos-
iting 60 nm Pd/Ti metal with the ratio about 9/1 by a co-sputtering
technique and patterned by a lift off process. Finally, the CNT-
interconnect construction was done by the O2 plasma etching for
single layer (SL) interconnect structure. Differing from the SL case,
the double layer (DL) interconnect structure was built with an
additional ALD made 1-nm-thick layer of Al2O3 deposited between
two CNT networks as depicted in Fig. 2(a). After patterning the
CNT-interconnects, the wafer was dipped into diluted HF solution
for 5 s to remove the top Al2O3 layer outside the interconnect re-
gimes before the O2 plasma etching. The detail process flow for
metal contact and interconnect of the DL samples formation is
shown in Fig. 3.
In this work, we fabricated four kinds of CNT-interconnect sam-
ples for comparison and further optimization: NR/SL, NR/DL, SR/SL
and SR/DL (The process for CNT network formation/ the intercon-
nect structure). It is noted that, in the SL case, an amount of
20 mL (40 cycles) CNT solution in total was applied for the CNT
network formation, while in the DL cases, the upper and bottom
CNT networks were separately fabricated by 10 mL (20 cycles)
CNT solution, as shown in Fig. 2(b).
Fig. 1. The CNT-interconnects fabricated by the SR/SL fabrication process with a
total amount of 20 mL CNT solution. (a) Conductance statistics of the width varying
series of CNT-interconnects. The inset is the specifications of the width varying
series: 100 lm in lengths and a range from 500 lm to 5 lm in widths. (b)
Conductance statistics of the length varying series of CNT-interconnects. The inset
is the specifications of the length varying series: 5 lm in widths and a range from
5 lm to 1000 lm in lengths. The square numbers of a CNT-interconnect are
determined by the length (L) divided by the width (W) of CNT-interconnects. (c) A
top view schematic a set of four-probe bridge resistors for a CNT-interconnect
conductance measurement. The spacing of 5 lm between two adjacent resistors is
for precise interconnect conductance measurement.
2 W.-C. Chiu, B.-Y. Tsui / Microelectronics Reliability xxx (2014) xxx–xxx
Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
http://dx.doi.org/10.1016/j.microrel.2013.12.024
3. 3. Results and discussions
3.1. Characterizations of CNT-interconnects by the NR/SL and the NR/
DL fabrication processes
Fig. 4 shows the conductance distribution and the histogram of
the width varying NR/SL and NR/DL samples. In this study, the
yield of CNT-interconnects was converted by the number of work-
ing interconnects in ten randomly selected samples for each condi-
tions. The statistical distribution in Fig. 4 shows that the average
sheet conductance of the NR/SL samples and the NR/DL samples
ranges from 6.79 Â 10À7
to 2.40 Â 10À6
S and from 4.70 Â 10À6
to
5.31 Â 10À5
S, respectively. Generally, the NR/DL samples have
higher conductance than that of the NR/SL samples under the same
CNT-interconnect square numbers. In addition, in some cases, the
conductance of the NR/DL samples gets more than one order
enhanced. Moreover, the conductance variations in the NR/DL sam-
ples are almost within one order except for some CNT-interconnect
samples with relatively long dimensions. In the inset of Fig. 4, all of
the NR/DL samples have overwhelmingly higher conductive prob-
abilities than those of the NR/SL samples. These results show that
the double layer interconnect structure is able to greatly improve
the performance of the CNT-interconnects with the normal spin
rate coated CNT networks.
The reasons for such satisfactory results might mainly arise
from the double layer interconnect structure. Past research has
proved that the Al2O3 could uniformly distribute and attach the
spin-coated CNTs on the wafer [23,24]. However, because of the fi-
nite stickiness from Al2O3 to CNTs, the deposited CNTs cannot
unlimitedly accumulate with the increase of coating cycles. There-
fore, some of coated CNTs would be thrown off the wafer during
such fast spinning process which eventually results in poor perfor-
mance of the CNT-interconnects in the single layer configuration.
In the case of the DL samples, the top 1-nm-thick layer of Al2O3
might supply extra stickiness to capture more spin-coated CNTs
onto the wafer which results in higher probabilities to form more
percolative paths. Additionally, unlike the single layer interconnect
structure, the electrons can only transport within single layer of a
CNT network, while the electrons in the double layer interconnect
structure can not only transmit via the tube-to-tube contact in the
same layer of the CNT network [25] but also tunnel through the top
Al2O3 layer to the other layer of the CNT network as depicted in
Fig. 5. According to the research from Saraswat’s group, the in-
serted 1-nm-thick Al2O3 layer does not form any resistance for
electron tunneling [26]. In this way, it is more likely for CNT-inter-
connects to possess more CNT connected conductive paths and
better electrical properties.
Fig. 6 shows the conductance distribution and the histogram of
the length varying NR/SL and NR/DL samples. The statistical distri-
bution in Fig. 6 shows that the average sheet conductance of the
NR/SL samples and the NR/DL samples ranges from 5.71 Â 10À6
to 9.98 Â 10À6
and from 7.34 Â 10À6
to 2.16 Â 10À5
, respectively.
In spite of the fact that the highest conductance values of the DL
samples in some cases are slightly lower than those of the SL sam-
ples, but the DL samples basically have higher conductance and
Fig. 2. (a) Schematic cross section of a CNT-interconnect in the double layer
configuration. The top and bottom CNT networks are formed by the normal rate or
the slow rate spin coating techniques with an amount of 10 mL CNT solution,
respectively. (b) A SEM image of a CNT network fabricated by the slow rate spin
coating with an amount of 20 mL CNT solution within an interconnect regime.
Fig. 3. A process flow for a double layer CNT-interconnect fabrication. (a)
Four-probe bridge resistors formation. (b) CNT-interconnect formation.
Fig. 4. Conductance statistics of the width varying series of CNT-interconnects built
with the single layer (red) and the double layer (blue) interconnect structures and
fabricated by a total amount of 20 mL CNT solution through the normal rate spin
coating. The inset is the histogram of the number of working CNT-interconnects in
the width varying series with the single layer (red) and the double layer (blue)
interconnect structures fabricated by a total amount of 20 mL CNT solution through
the normal rate spin coating. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
W.-C. Chiu, B.-Y. Tsui / Microelectronics Reliability xxx (2014) xxx–xxx 3
Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
http://dx.doi.org/10.1016/j.microrel.2013.12.024
4. more concentrated conductance distributions in most cases. How-
ever, the relatively larger than width varying CNT-interconnect
conductance variations could be ascribed to the thin layer of
Al2O3 inserted between the two CNT networks. In a CNT random
network, the carrier transportation is dominated by the tube-to-
tube Schottky emission [24], but the interconnects with the double
layer structure has one more tunneling barrier from the top layer
of Al2O3 apart from the resistance coming from the metallic/semi-
conducting CNT interface [27]. Besides, compared with the width
varying series of CNT-interconnects, the interconnect areas in
length varying series are smaller, so that it is more difficult to
accommodate sufficient CNTs and less likely for these limited
number of the CNTs within the interconnect regime to link into
conductive paths which eventually results in lower conductance
and larger conductance variations of the DL samples.
However, it is worthy to note that the double layer structure
renders the relatively high conductive probabilities to CNT-inter-
connects especially to the interconnects with a large number of
square numbers, such as 70% in 100 square numbers and 60% in
200 square numbers as shown in the inset of Fig. 6. Such high con-
ductive probabilities of the long dimensional CNT-interconnects
might also attribute to the extra stickiness to CNTs and the uni-
formly distributing CNT ability from the top layer of Al2O3 in dou-
ble layer structure.
3.2. Phase transitions in the size dependent conductivities of the NR/SL
and the NR/DL CNT-interconnects
The conductive property of a large amount of randomly dispers-
ing conductible and quasi one-dimensionally structural CNTs with-
in a specified interconnect regime could be analyzed by the
percolation theory [28,29] and expressed as follows [30]:
r / ðN À NcÞa
; ð1Þ
where r stands for the conductivity of a CNT-interconnect with the
CNT density of N, and Nc is the critical CNT density. This is a thresh-
old for the CNTs to connect into a least one conductive paths in a
specific CNT cluster. The critical exponent, a is a space geometri-
cally dependent parameter, and an exponent of 1.33 is theoretically
for a conductive film in two dimensions while 1.94 in three dimen-
sions. The critical density for the percolative model is given by
l
ffiffiffiffiffiffiffiffiffi
pNc
p
¼ 4:236; ð2Þ
where l is the average length of the CNTs. In 2004, the Grüner group
used percolation theory to investigate the phase transition phenom-
ena occurring in the CNT density dependent conductivities and dis-
tinguish the percolation region from the power region by the power
fitting approach [30]. In 2013, we also took advantage of a similar
method to prove that under a specified times of slow rate spin coat-
ing cycles for CNT-interconnect formation, varying the interconnect
regime has a similar effect as the change of the CNT density and rea-
sonably drew a conclusion about the equivalence of the CNT density
with the reciprocal of the square number of CNT-interconnects. In
addition, we also defined the critical square number to correspond
to the critical density (percolation threshold) in the percolative rela-
tion. In this way, it is more legitimate to apply the percolation the-
ory to the conductivities of the size varying CNT-interconnects [20].
Moreover, we further categorized the conductive characteristics of
the CNT-interconnects into linear region, power region and percola-
tion region with the increase of the CNT-interconnect square num-
ber [20]. However, differing from the SL CNT-interconnects, the DL
interconnect structure builds CNT-interconnects into three dimen-
sional conductive films. Therefore, it should be noticed that the
power region of the DL samples is distinguished out by which the
exponents of the fitting curve approaching or deviating 1.94 instead
of 1.33.
Fig. 7 shows the fitting curves of average conductance of the
width varying CNT-interconnects fabricated by the NR/SL and the
NR/DL fabrication processes. By applying the power fitting ap-
proach, all sampling CNT-interconnects by the NR/SL fabrication
process are sorted into percolation region because the exponents
deviated from 1.33, when the fitting curve included less and less
points excluding from the CNT-interconnects of L Â W = 100 lm
 500 lm. On the other hand, the exponents of the fitting curve
for the CNT-interconnects by the NR/DL fabrication process gradu-
ally closed to 1.94 after 100 lm  5 lm, 100 lm  7 lm, 100 lm
 10 lm, 100 lm  12 lm, 100 lm  17 lm and 100 lm  20 lm
interconnects were filtered out one by one which implies that these
points are categorized into the percolation region, while the rest
samples are around the power region. These results demonstrate
that not only the interconnect size but also the interconnect struc-
ture would affect the characteristics of CNT-interconnects.
Fig. 8 shows the fitting curves of average conductance of the
length varying CNT-interconnects fabricated by the NR/SL and
the NR/DL fabrication processes. In this figure, all of the CNT-inter-
connects by the NR/SL fabrication process belongs to the percola-
tion region also due to the deviation of the exponent from 1.33.
In the length varying series of CNT-interconnects, owing to the
smaller interconnect areas, the more influential resistance from
Fig. 5. Schematic electron transmission mechanisms of the CNT-interconnects with
the double layer structure: (a) tunneling to the other layer of CNT network (b) tube-
to-tube contact transfer in the same layer of CNT network.
Fig. 6. Conductance statistics of the length varying series of CNT-interconnects
built with the single layer (red) and the double layer (blue) interconnect structures
and fabricated by a total amount of 20 mL CNT solution through the normal rate
spin coating. The inset is the histogram of the number of working CNT-intercon-
nects in the length varying series with the single layer (red) and the double layer
(blue) interconnect structures fabricated by a total amount of 20 mL CNT solution
through the normal rate spin coating. (For interpretation of the references to colour
in this figure legend, the reader is referred to the web version of this article.)
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Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
http://dx.doi.org/10.1016/j.microrel.2013.12.024
5. the extra layer of Al2O3 and resistance between CNTs bring about
the linear related conductance with a critical exponent of 1.04 [31].
3.3. Characterizations of CNT-interconnects by the SR/SL and the SR/DL
fabrication processes
Fig. 9 shows the conductance distribution and the histogram of
the width varying SR/SL and SR/DL samples. The statistical
distribution in Fig. 9 shows that the average sheet conductance
of the SR/SL samples and the SR/DL samples ranges from
3.16 Â 10À5
to 5.22 Â 10À5
S and from 9.29 Â 10À6
to
5.64 Â 10À5
S, respectively. Compared with the CNT-interconnects
fabricated by the normal rate spin coating process, the SR samples
generally have higher conductance under the same square
numbers of CNT-interconnects. It is believed that most of CNTs
in solution during the slow rate spin coating process would be held
on the substrate, so that the extra layer of Al2O3 in DL samples
demonstrates less superiority on the electrical performance than
the case of the normal rate spin coating. Conversely, it becomes
additional resistance to slightly lower the conductance of the DL
samples. However, the weak Van der Waals forces between the
CNTs causes some dispersed CNTs to bundle together before pre-
cipitation which leads in relatively higher conductance variations
in the SL samples [32]. Therefore, it is concluded that the double
layer structure could be effective to reduce the conductance varia-
tions. On the other hand, the inset of Fig. 9 shows that, in terms of
the conductive probability, the performance of the SR/DL samples
is competitive with that of the SR/SL samples. Both CNT-intercon-
nect samples have above 60% of conductive probabilities under the
same square numbers which verify that CNT-interconnects fabri-
cated by the slow rate spin coating are likely to possess more
CNT-linked conductive paths than those fabricated by the normal
rate spin coating.
Fig. 7. Power functions of the average conductance versus the square number of the
width varying CNT-interconnects with the single layer (red) or the double layer
(blue) interconnect structures fabricated by a total amount of 20 mL CNT solution
through the normal rate spin coating. In the width varying series, all SL samples are
classified into the percolation region, while the DL samples with less than four
square numbers belong to the power region and the rest CNT-interconnects are
around the percolation region. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
Fig. 8. Power functions of the average conductance versus the square number of the
length varying CNT-interconnects with the single layer (red) or the double layer
(blue) interconnect structures fabricated by a total amount of 20 mL CNT solution
through the normal rate spin coating. In the length varying series, all SL samples are
sorted into the percolation region while all DL samples proceeds to the linear region
because of the resistance from the top layer of Al2O3 and mutual CNT contacts. (For
interpretation of the references to colour in this figure legend, the reader is referred
to the web version of this article.)
Fig. 9. Conductance statistics of the width varying series of CNT-interconnects built
with the single layer (red) and the double layer (blue) interconnect structures and
fabricated by a total amount of 20 mL CNT solution through the slow rate spin
coating. The inset is the histogram of the number of working CNT-interconnects in
the width varying series with the single layer (red) and the double layer (blue)
interconnect structures fabricated by a total amount of 20 mL CNT solution through
the slow rate spin coating. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
Fig. 10. Conductance statistics of the length varying series of CNT-interconnects
built with the single layer (red) and the double layer (blue) interconnect structures
and fabricated by a total amount of 20 mL CNT solution through the slow rate spin
coating. The inset is the histogram of the number of working CNT-interconnects in
the length varying series with the single layer (red) and the double layer (blue)
interconnect structures fabricated by a total amount of 20 mL CNT solution through
the slow rate spin coating. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
W.-C. Chiu, B.-Y. Tsui / Microelectronics Reliability xxx (2014) xxx–xxx 5
Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
http://dx.doi.org/10.1016/j.microrel.2013.12.024
6. Fig. 10 shows the conductance distribution and the histogram of
the length varying SR/SL and SR/DL samples. The statistical distri-
bution in Fig. 10 shows that the average sheet conductance of the
SR/SL samples and the SR/DL samples ranges from 1.50 Â 10À5
to
1.21 Â 10À4
S and from 9.29 Â 10À6
to 4.02 Â 10À5
S, respectively.
Like the case of the width varying CNT-interconnect case, most
SL samples have higher conductance than that of the DL samples.
However, in the length varying case, the conductance distribution
of the DL samples seems more dispersed than those of the SL sam-
ples. The failure of the double layer structure might be ascribed to
the top layer of Al2O3 between the two CNT networks as well. Be-
cause the slow rate spin-coated CNTs could be effectively kept on
the wafer, the CNT density of the SL samples would be twice higher
than that of each layer in the DL samples. Besides, the current con-
duction in the SL samples could be just directly via the tube-to-
tube contact, but the electrons might need to continually tunnel
through the top Al2O3 layer up and down to complete the whole
transmission. Therefore, there is no apparent enhancement in the
conductance values and distributions of the DL samples. Nonethe-
less, there are two points worth highlighting. One is that the range
of the average sheet conductance of the width varying DL samples
almost overlaps with that of the length varying DL samples fabri-
cated by the normal rate or slow rate spin-coated CNT networks,
and the CNT-interconnects with 100 and 200 square numbers have
an average sheet conductance of about 1.94 Â 10À5
S and
1.85 Â 10À5
S with the conductive probabilities of 50% and 40%,
respectively, as demonstrated in the inset of Fig. 10. These results
once again show that the double layer structure could not only
strengthen the stickiness to CNTs but also disperse the CNTs more
uniformly on the wafer. In this way, it is likely for more CNTs to
participate in the connection of conductive paths and make higher
reliabilities of CNT-interconnects and higher conductive probabili-
ties of the long dimensional CNT-interconnects.
3.4. Phase transitions in the size dependent conductivities of the SR/SL
and the SR/DL CNT-interconnects
Fig. 11 shows the fitting curves of average conductance of the
width varying CNT-interconnects fabricated by the SR/SL and the
SR/DL fabrication processes. Because of the high CNT densities in
the CNT-interconnects fabricated by the slow rate spin coating
process, all of the SL and DL samples proceeds into power region
and linear region also determined by the power fitting approach.
The power region of the DL samples includes 100 lm  25 lm,
100 lm  20 lm, 100 lm  17 lm, 100 lm  12 lm, 100 lm
 10 lm, 100 lm  7 lm and 100 lm  5 lm with the exponent
of 1.86.
Fig. 12 shows the fitting curves of average conductance of the
length varying CNT-interconnects fabricated by the SR/SL and the
SR/DL fabrication processes. As we have shown, the shrinkage of
the interconnect area would strengthen the influence of resistance
from the interlayer of Al2O3 and the metallic/semiconducting CNT
interfaces which leads to the enlargement of the linear region of
the length varying DL samples.
4. Conclusions
In this work, we have fabricated the CNT-interconnects with
two kinds of CNT network formation processes, the normal rate
and the slow rate spin coating, and two kinds of interconnect struc-
tures, the single layer and the double layer interconnect structure,
and demonstrated the performance of CNT-interconnects with four
combinations of the processes. By the percolation theory, we illus-
trated the interconnect size, the structure and the processes for the
CNT network formation dependent phase transition phenomena
and classified into three regions based on the characterizations.
In the case of the CNT networks formed by the normal rate spin
coating, the DL samples generally shows better conductivity, nar-
rower variations, better conductivity reliabilities and higher con-
ductive probabilities. On the other hand, in the case of the CNT
networks formed by the slow rate spin coating, even though the
DL samples shows slightly worse conductivity but narrower varia-
tions, better conductivity reliabilities and higher probabilities
especially for the CNT-interconnects with large square numbers
still make the double layer interconnect structure very attractive.
It should be noted that the smaller CNT-interconnect area, the lar-
ger the conductance variations of the DL samples would be. Finally,
although the spin coating process and the multi-layer interconnect
structure demonstrate some advantages to the CNT-interconnects,
we cannot but admit that the conductivity of CNT-interconnects
with multi-layer interconnect structure is still much lower than
that of copper, 5.88 Â 105
S/cm. However, the application of
CNT-interconnects to flexible electronics and wearable electronics
Fig. 11. Power functions of the average conductance versus the square number of
the width varying CNT-interconnects with the single layer (red) or the double layer
(blue) interconnect structures fabricated by a total amount of 20 mL CNT solution
through the slow rate spin coating. In the width varying series, the SL sample with
0.2 square numbers and the DL samples with less two square numbers are classified
into the linear region, while the rest SL and DL samples are around the power
region. The larger linear region of the DL samples arises from the resistance from
the top layer of Al2O3. (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)
Fig. 12. Power functions of the average conductance versus the square number of
the length varying CNT-interconnects with the single layer (red) or the double layer
(blue) interconnect structures fabricated by a total amount of 20 mL CNT solution
through the slow rate spin coating. In the length varying series, all SL samples locate
at the power region, while the DL samples with less than 100 square numbers are
around the linear region. (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)
6 W.-C. Chiu, B.-Y. Tsui / Microelectronics Reliability xxx (2014) xxx–xxx
Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
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7. is still very promising [33,34]. Therefore, in order to optimize the
performance of CNT-interconnects with the multi-layer intercon-
nect structure, the further work might concern with maximizing
the conductance of each single layer of CNT networks (increasing
the spin coating cycles), minimizing the resistance from the inter-
layer of Al2O3, or introducing more interlayer of Al2O3 into
CNT-interconnects.
Acknowledgements
The authors would like to thank the Nano Facility Center of Na-
tional Chiao-Tung University for providing the experimental facil-
ities. This work was supported in part by the Ministry of Education
in Taiwan under ATU Program, and was supported in part by the
National Science Council, Taiwan, ROC under the contract No.
NSC 100-2221-E-009- 010-MY2.
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Please cite this article in press as: Chiu W-C, Tsui B-Y. High performance of CNT-interconnects by the multi-layer structure. Microelectron Reliab (2014),
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