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Large Scale Controlled Placement of Nanoparticles and Nanostructure
IB-2047
APPLICATIONS OF TECHNOLOGY:
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(a) Image of arrays of nanoscale torsional actuators using the Berkeley Lab controlled, nanotube placement technique. An individual actuator consist of two anchors, a suspended MWCNT, a suspended metal mirror or paddle, and the conducting back gate buried beneath the surface. The array was created by placing one nanotube per activated region – in this case the region is a dot. The device was then fabricated with the nanotubes in place. (b) Increased magnification image of the nanotube device marked with a black box in (a). |
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- Manufacturing MEMS and NEMS devices, e.g. arrays, solar collectors, nanoscale memory and optical switching devices, field emitters, chemical or mass sensors, LEDs, flexible interconnects, mechanical filters, microfluidic pumps and gates
ADVANTAGES:
- Allows precision placement of high quality, preprocessed, or functionalized nanoparticles or nanostructures
- Simple chemistry integrates into standard silicon and large scale multilayer processes
- Can be used with a variety of conventional substrates
- Does not require complex chemically or geometrically modified substrates
DESCRIPTION:
Alex Zettl and coworkers have developed a technique for large scale placement of highly aligned nanotubes, nanowires, and other nanoparticles and nanostructures on precisely defined areas of a substrate. This low temperature process for creating nanoarrays and other ordered configurations has been demonstrated on silicon-oxide surfaces and promises to enable the incorporation of high quality nanoparticles into standard semiconductor processing.
Unlike other methods for creating nanoarrays, the Berkeley Lab invention can incorporate unfunctionalized or pre-functionalized nanoparticles without altering their chemistries. Furthermore, the substrates do not have to withstand high temperatures or have altered topography and the adhesion chemistry is simple and scalable.
In the Berkeley Lab process, portions of a thin layer of polymer on a substrate are exposed to precisely delivered electron beam radiation. A suspension of nanoparticles is then spin coated onto the substrate. The nanoparticles selectively adhere to the exposed portions of the polymer layer and are aligned in the direction of the flow. The thin layer of polymer may consist of a resist composition that is already present in standard lithographic work and permits patterning, in this case using a scanning electron microscope (SEM).
Zettl’s group has shown that nanotubes placed using this technique remain in position after further processing, including etching, metal deposition, and the addition of barrier or doping layers.
STATUS:
- Patent pending. Available for licensing or collaborative research.
FOR MORE INFORMATION:
Yuzvinsky, T.D., Fennimore, A.M., Kis, A., Zettl, A., “Controlled Placement of Highly Aligned Carbon Nanotubes for the Manufacture of Arrays of Nanoscale Torsional Actuators,” Nanotechnology 2006, 17, 434-438.
REFERENCE NUMBER: IB-2047
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Scalable Cleaning, Reforming, and Shaping of Batch-Manufactured Nanotubes and Nanowires
IB-2144
APPLICATIONS OF TECHNOLOGY:
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A series of TEM images showing the evolution of a MWCNT device over time. ( a) Gold nanoparticles cover the as-fabricated device. (b) The device is partially cleaned by the application of 1.7 V 190 A . (c) Increasing the voltage to 1.72 V cleans the device further. (d) Raising the voltage to 1.9 V cleans the device of all gold nanoparticles. |
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ADVANTAGES:
- Generates high quality nanotubes and nanowires with superior bonding, mechanical, thermal, and conductive properties
- Enables easy customization of nanotube geometry
- Can be applied to individual or bundled nanotubes
DESCRIPTION:
Alex Zettl and his team have devised a technique for generating clean, high quality, and shaped nanotubes from those generated by bulk growth or processing methods. This electrical treatment is the first simple, reliable, and scalable method for removing contaminants from dirty nanotubes, reforming defective nanotubes, and adding permanent kinks and hooks.
The Berkeley Lab invention employs current induced heating to purify nanotubes and/or forge them into a variety of shapes useful for applications such as MEMS components, memory devices, nanoarrays, sensors, mechanical reinforcement, nano-hooks and loops, and all-in-one atomic force microscope cantilevers and tips.
STATUS:
FOR MORE INFORMATION SEE:
Yuzvinsky, T. D., Mickelson, W., Aloni, S., Konsek, S. L., Fennimore, A. M., Begtrup, G. E., Kis, A., Regan, B. C., Zettl, A., “Imaging the Life Story of Nanotube Devices,” Appl. Phys. Lett. 2005, 87, 083103.
REFERENCE NUMBER: IB-2144
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Defect Elimination in Nanoscale Materials
IB-2125
APPLICATIONS OF TECHNOLOGY:
- Generating defect-free nanotubes or nanowires with superior mechanical, thermal, and electrical properties for devices such as MEMS/NEMS, ICs, and resistors, as well as for ultimate-strength materials
- Creating sophisticated heterojunctions in a MWNT by refining specific sections and not others
ADVANTAGES:
- Allows control of nanotube diameter, length, defect concentration, and thermal and electrical conductivity
- Improves the quality of MWNTs and nanowires
- Easily scalable, low temperature process
DESCRIPTION:
Bulk synthesis techniques have been unable to offer fully controlled growth of multiwall carbon nanotubes (MWNT) and other nanomaterials such as nanowires, yet this type of quality control will be required for many commercial nanomaterial applications. Alex Zettl and his team at Berkeley Lab have developed a low temperature, scalable method of refining MWNTs to produce nanotubes with superior mechanical and electrical properties and to generate heterojunctions within the tubes which serve as schottky interfaces or p/n junctions.
In the Berkeley Lab refinement process, a carbon-loaded catalyst particle is either incorporated into each original MWNT via the original synthesis process or inserted later. An electrical current is passed through the tubes, driving the melted catalyst beads down the tube. The catalyst bead consumes and re-forms the original low-grade nanotube as it migrates, ejecting a higher quality MWNT from the trailing end. Because the carbon particles in the catalyst are replenished, defect-free nanotubes as long as the original tube can be generated. The electrical current determines the speed of the nanotube formation or refinement, which in turn allows control of the tube’s defect concentration, and therefore, its electrical, thermal, and mechanical properties. The catalysts can be left on the nanotube or removed through acid etching.
STATUS:
- Patent pending. Available for licensing or collaborative research.
FOR MORE INFORMATION SEE:
Jensen, K., Mickelson, W., Han, W., Zettl, A. “Current-Controlled Nanotube Growth and Zone Refinement,” App. Phys. Lett. 2005, 86, 173107.
REFERENCE NUMBER: IB-2125
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Nanoknife: The Precision Cutting of Molecular-scale Materials
IB-2068
APPLICATIONS OF TECHNOLOGY:
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Composite TEM micrographs of a nanotube cut using the Berkeley Lab method. |
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- Precise cutting and tailoring of small scale structures and devices
- Tailoring nanostructures/nanomaterials to create field emitters, quantum dots, nanoscale resonators, electrical interconnects and circuitry, linear and rotational bearings, NEM/MEMS components, scanning probe microscopy tips, and to control nanotube strength or conductivity
- Removing excess nanomaterial when a single electrical or mechanical contact is desired
ADVANTAGES:
- Uses less expensive and widely available SEMs instead of TEMs
- Damage is more discriminate than with chemical etching or electrical methods (accuracy within 10 nm)
- Cuts delicate and irregular nanomaterials that cannot be imaged by STM or AFM
- Compatible with most device architectures
- More time efficient than scanning probe methods
DESCRIPTION:
Alex Zettl and his group at Berkeley Lab have invented a rapid method to cut and hinge carbon nanostructures and other materials like graphite sheets using the low energy focused electron beam of a scanning electron microscope (SEM). Until now, no simple and flexible method has existed for cleanly cutting and shaping nanomaterials. The new method could enable the creation of more complex nano-circuitry, field emitters, bearings for nanoscale linear and rotational actuators, higher resolution AFM and STM tips, and a multitude of tailored MEMS/NEMS components.
The Berkeley Lab technique is highly precise, with accuracies as high as 10 nm, and delivers minimal damage to surrounding material and untargeted sections of the particle being cut. Unlike TEM and scanning probe shaping methods, the new invention imposes no special substrate requirements and is therefore compatible with most device architectures. Single or multiple nanotubes can be loaded, located, and cut within several minutes.
STATUS:
FOR MORE INFORMATION SEE:
Yuzvinsky, T.D., Fennimore, A.M., Mickelson, W., Esquivias, C. Zettl, A., “Precision Cutting of Nanotubes with a Low Energy Electron Beam,” Appl. Phys. Lett., 2005, 86, 053109.
REFERENCE NUMBER: IB-2068
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