Engineering Commons^™

Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson

Thomas E. Wilson

Progress is described in experiments to generate coherent terahertz acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation. Future experiments are proposed that would use the superlattice as a transducer in a terahertz cryogenic acoustic reflection microscope with sub-nanometer resolution.

Exploring Public Values Implications Of The I-Corps Program, Jan Youtie, Philip Shapira

Philip Shapira

Polarization At Metal--Biomolecular Interfaces In Solution, Hendrik Heinz, Kshitij Jha, Jutta Luettmer-Strathmann, Barry Farmer, Rajesh Naik

Jutta Luettmer-Strathmann

Metal surfaces in contact with water, surfactants and biopolymers experience attractive polarization owing to induced charges. This fundamental physical interaction complements stronger epitaxial and covalent surface interactions and remains difficult to measure experimentally. We present a first step to quantify polarization on even gold (Au) surfaces in contact with water and with aqueous solutions of peptides of different charge state (A3 and Flg-Na3) by molecular dynamics simulation in all-atomic resolution and a posteriori computation of the image potential. Attractive polarization scales with the magnitude of atomic charges and with the length of multi-poles in the aqueous phase such as the …

Uv-Absorption And Silica/Titania Colloids Using A Core--Shell Approach, Liang Zhou, Hendrik Heinz, Mark Soucek, Elvin Aleman, David Modarelli

David A. Modarelli

Metal-oxo-colloids have been prepared using tetraethoxysilane (TEOS) oligomers with titanium tetra-i-propoxide (TIP) or titanium (di-i-propoxide) bis(acetylacetonate) (TIA) precursors. Transmission electron microscopy (TEM), FTIR, UV-Vis, and photoluminescence spectroscopy were used to investigate the composition, the size, and optical properties of the Si/Ti core–shell colloids. The presence of hetero-bonded silicate structure (Si–O–Ti) was indicated by FTIR spectroscopy. The size of Si/TIP system ranged from 55 to 120 nm and Si/TIA system ranged from 220 to 250 nm. The TEM data indicated that the size of colloids can be controlled by the TIP or TIA content. The Si/Ti system …

High-Throughput Screening Of Shape Memory Alloy Thin-Film Spreads Using Nanoindentation, Arpit Dwivedi, Thomas Wyrobek, Oden Warren, Jason Hattrick-Simpers, Olubenga Famodu, Ichiro Takeuchi

Jason R. Hattrick-Simpers

We have demonstrated the utility of nanoindentation as a rapid characterization tool for mapping shape memoryalloy compositions in combinatorial thin-film libraries. Nanoindentation was performed on Ni–Mn–Al ternary composition spreads. The indentation hardness and the reduced elastic modulus were mapped across a large fraction of the ternary phase diagram. The large shape memoryalloy composition region, located around the Heusler composition (Ni2MnAl), was found to display significant departure in these mechanical properties from the rest of the composition spread. In particular, the modulus and the hardness values are lower for the martensite region than those of the rest of the phase diagram.

The Materials Super Highway: Integrating High-Throughput Experimentation Into Mapping The Catalysis Materials Genome, Jason Hattrick-Simpers, Cun Wen, Jochen Lauterbach

Jason R. Hattrick-Simpers

No abstract provided.

A Study Of Titania Nanotube Synthesis In Chloride-Ion-Containing Media, E. Panaitescu, C. Richter, L. Menon

Eugen Panaitescu

We have completed a detailed experimental investigation into the recently discovered synthesis of titania nanotubes in chloride-ion-containing media. We show that the role of the chloride ions is catalytic and it has a strong effect in increasing the reactivity of the solution, while the nature of cations has no visible role. We have identified the critical parameters for optimal growth and fast production of nanotubes, and a basic growth mechanism for the tubes is proposed. This opens routes for significant improvements of the method toward uniformity and/or better overall yield, making it a viable alternative to the present established methods.

Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen

Albert B Chen

Dielectric thin films in nanodevices may absorb moisture, leading to physical changes and property/performance degradation, such as altered data storage and readout in resistance random access memory. Here we demonstrate using a nanometallic memory that such degradation proceeds via nanoporosity, which facilitates water wetting in otherwise nonwetting dielectrics. Electric degradation only occurs when the device is in the charge-storage state, which provides a nanoscale dielectrophoretic force directing H2O to internal field centers (sites of trapped charge) to enable bond rupture and charged hydroxyl formation. While these processes are dramatically enhanced by an external DC or AC field and electron-donating electrodes, …

Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar

Srinivas Sridhar

Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.

Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar

Donald Heiman

Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.

Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. Bennett, L. Menon, D. Heiman

Donald Heiman

Ordered arrays of GaMnAs magnetic semiconductor nanodots have been fabricated using anodic porous alumina templates as etch masks. The magnetic behavior is studied for prepared arrays with 40 nm dot diameter, 15 nm dot thickness, and 80 nm periodicity. The disklike nanodots exhibit an easy axis for fields applied in the radial direction and a hard axis in the smaller direction. In the radial direction superparamagnetism is observed with a blocking temperature of 30 K. The fabrication technique is convenient for preparing nanodot arrays of compound semiconductors that cannot be formed by self-assembly techniques.

Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar

Latika Menon

Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.

Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. P. Bennett, L. Menon, D. Heiman

Latika Menon

Ordered arrays of GaMnAs magnetic semiconductor nanodots have been fabricated using anodic porous alumina templates as etch masks. The magnetic behavior is studied for prepared arrays with 40 nm dot diameter, 15 nm dot thickness, and 80 nm periodicity. The disklike nanodots exhibit an easy axis for fields applied in the radial direction and a hard axis in the smaller direction. In the radial direction superparamagnetism is observed with a blocking temperature of 30 K. The fabrication technique is convenient for preparing nanodot arrays of compound semiconductors that cannot be formed by self-assembly techniques.

A Study Of Titania Nanotube Synthesis In Chloride-Ion-Containing Media, E. Panaitescu, C. Richter, L. Menon

Latika Menon

We have completed a detailed experimental investigation into the recently discovered synthesis of titania nanotubes in chloride-ion-containing media. We show that the role of the chloride ions is catalytic and it has a strong effect in increasing the reactivity of the solution, while the nature of cations has no visible role. We have identified the critical parameters for optimal growth and fast production of nanotubes, and a basic growth mechanism for the tubes is proposed. This opens routes for significant improvements of the method toward uniformity and/or better overall yield, making it a viable alternative to the present established methods.

High-Throughput Assembly Of Nanoelements In Nanoporous Alumina Templates, Evin Gultepe, Dattatri K. Nagesha, Latika Menon, Ahmed A. Busnaina, Srinivas Sridhar

Srinivas Sridhar

The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50 nm inside nanopore arrays of height of 250 nm and diameter of 80 nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.

Directed Assembly Of Gold Nanoparticle Nanowires And Networks For Nanodevices, Xugang Xiong, Ahmed A. Busnaina, Selvapraba Selvarasah, Sivasubramanian Somu, Ming Wei, Joey Mead, Chia-Ling Chen, Juan Aceros, Prashanth Makaram, Mehmet R. Dokmeci

Sivasubramanian Somu

Alternating electric field is used to assemble gold nanoparticle nanowires from liquid suspensions. The effects of electrode geometry and the dielectrophoresis force on the chaining and branching of nanowire formation are investigated. The nanowire assembly processes are modeled using finite element calculations, and the particle trajectories under the combined influence of dielectrophoresis force and viscous drag are simulated. Nanoparticle nanowires with 10 nm resolution are fabricated. The wires can be further oriented along an externally introduced flow. This work provides an approach towards rapid assembly and organization of ultrasmall nanoparticle networks.

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer

Sivasubramanian Somu

The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.

Low-Voltage And Short-Channel Pentacene Field-Effect Transistors With Top-Contact Geometry Using Parylene-C Shadow Masks, Yoonyoung Chung, Boris Murmann, Selvapraba Selvarasah, Mehmet Dokmeci, Zhenan Bao

Mehmet R. Dokmeci

We have fabricated high-performance top-contact pentacene field-effect transistors using a nanometer-scale gate dielectric and parylene-C shadow masks. The high-capacitance gate dielectric, deposited by atomic layer deposition of aluminum oxide, resulted in a low operating voltage of 2.5 V. The flexible and conformal parylene-C shadow masks allowed fabrication of transistors with channel lengths of L = 5, 10, and 20 μm. The field-effect mobility of the transistors was μ = 1.14 (±0.08) cm²/V s on average, and the IMAX/IMIN ratio was greater than 10⁶.

High-Throughput Assembly Of Nanoelements In Nanoporous Alumina Templates, Evin Gultepe, Dattatri K. Nagesha, Latika Menon, Ahmed A. Busnaina, Srinivas Sridhar

Dattatri K. Nagesha

The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50 nm inside nanopore arrays of height of 250 nm and diameter of 80 nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.

Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet Dokmeci

Sinan Müftü

Carbon nanotube networks are an emerging conductive nanomaterial with applications including thin film transistors, interconnects, and sensors. In this letter, we demonstrate the fabrication of single-walled carbon nanotube (SWNT) networks on a flexible polymer substrate and then provide encapsulation utilizing a thin parylene-C layer. The encapsulated SWNT network was subjected to tensile tests while its electrical resistance was monitored. Tests showed a linear-elastic response up to a strain value of 2.8% and nearly linear change in electrical resistance in the 0%–2% strain range. The networks’ electrical resistance was monitored during load-unload tests of up to 100 cycles and was hysteresis-free.

High-Throughput Assembly Of Nanoelements In Nanoporous Alumina Templates, Evin Gultepe, Dattatri K. Nagesha, Latika Menon, Ahmed A. Busnaina, Srinivas Sridhar

Latika Menon

The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50 nm inside nanopore arrays of height of 250 nm and diameter of 80 nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer

Ahmed A. Busnaina

The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.

Directed Assembly Of Gold Nanoparticle Nanowires And Networks For Nanodevices, Xugang Xiong, Ahmed A. Busnaina, Selvapraba Selvarasah, Sivasubramanian Somu, Ming Wei, Joey Mead, Chia-Ling Chen, Juan Aceros, Prashanth Makaram, Mehmet R. Dokmeci

Ahmed A. Busnaina

Alternating electric field is used to assemble gold nanoparticle nanowires from liquid suspensions. The effects of electrode geometry and the dielectrophoresis force on the chaining and branching of nanowire formation are investigated. The nanowire assembly processes are modeled using finite element calculations, and the particle trajectories under the combined influence of dielectrophoresis force and viscous drag are simulated. Nanoparticle nanowires with 10 nm resolution are fabricated. The wires can be further oriented along an externally introduced flow. This work provides an approach towards rapid assembly and organization of ultrasmall nanoparticle networks.

High-Throughput Assembly Of Nanoelements In Nanoporous Alumina Templates, Evin Gultepe, Dattatri K. Nagesha, Latika Menon, Ahmed A. Busnaina, Srinivas Sridhar

Ahmed A. Busnaina

The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50 nm inside nanopore arrays of height of 250 nm and diameter of 80 nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer

Nicol E. McGruer

The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.

Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet R. Dokmeci

Yung Joon Jung

Carbon nanotube networks are an emerging conductive nanomaterial with applications including thin film transistors, interconnects, and sensors. In this letter, we demonstrate the fabrication of single-walled carbon nanotube (SWNT) networks on a flexible polymer substrate and then provide encapsulation utilizing a thin parylene-C layer. The encapsulated SWNT network was subjected to tensile tests while its electrical resistance was monitored. Tests showed a linear-elastic response up to a strain value of 2.8% and nearly linear change in electrical resistance in the 0%–2% strain range. The networks’ electrical resistance was monitored during load-unload tests of up to 100 cycles and was hysteresis-free.

Parallel Arrays Of Individually Addressable Single-Walled Carbon Nanotube Field-Effect Transistors, Sarah Lastella, Govind Mallick, Raymond Woo, Shashi Karna, David Rider, Ian Manners, Yung-Joon Jung, Chang Ryu, Pulickel Ajayan

Yung Joon Jung

High-throughput field-effect transistors (FETs) containing over 300 disentangled, high-purity chemical-vapor-deposition-grown single-walled carbon nanotube (SWNT) channels have been fabricated in a three-step process that creates more than 160 individually addressable devices on a single silicon chip. This scheme gives a 96% device yield with output currents averaging 5.4 mA and reaching up to 17 mA at a 300 mV bias. Entirely semiconducting FETs are easily realized by a high current selective destruction of metallic tubes. The excellent dispersity and nearly-defect-free quality of the SWNT channels make these devices also useful for nanoscale chemical and biological sensor applications.

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer

Yung Joon Jung

The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.

Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet R. Dokmeci

Mehmet R. Dokmeci

Carbon nanotube networks are an emerging conductive nanomaterial with applications including thin film transistors, interconnects, and sensors. In this letter, we demonstrate the fabrication of single-walled carbon nanotube (SWNT) networks on a flexible polymer substrate and then provide encapsulation utilizing a thin parylene-C layer. The encapsulated SWNT network was subjected to tensile tests while its electrical resistance was monitored. Tests showed a linear-elastic response up to a strain value of 2.8% and nearly linear change in electrical resistance in the 0%–2% strain range. The networks’ electrical resistance was monitored during load-unload tests of up to 100 cycles and was hysteresis-free.

Directed Assembly Of Gold Nanoparticle Nanowires And Networks For Nanodevices, Xugang Xiong, Ahmed A. Busnaina, Selvapraba Selvarasah, Sivasubramanian Somu, Ming Wei, Joey Mead, Chia-Ling Chen, Juan Aceros, Prashanth Makaram, Mehmet R. Dokmeci

Mehmet R. Dokmeci

Alternating electric field is used to assemble gold nanoparticle nanowires from liquid suspensions. The effects of electrode geometry and the dielectrophoresis force on the chaining and branching of nanowire formation are investigated. The nanowire assembly processes are modeled using finite element calculations, and the particle trajectories under the combined influence of dielectrophoresis force and viscous drag are simulated. Nanoparticle nanowires with 10 nm resolution are fabricated. The wires can be further oriented along an externally introduced flow. This work provides an approach towards rapid assembly and organization of ultrasmall nanoparticle networks.