TECHNOLOGY AREAS: Materials/Processes, Sensors, Electronics

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: The purpose of this effort is to develop a means for producing large volumes of single-walled carbon nanotubes that are monodisperse in their diameter, bandgap, and/or electronic type.

DESCRIPTION: Single-walled carbon nanotubes (SWCNTs) possess unique properties which make them ideal for use in a variety of applications including:

(1) Electrical properties: SWCNTs can be metallic or semiconducting. The metallic SWCNTs are immune from electromigration at high current densities, thus making them ideal materials for interconnects in integrated circuits. In addition, the semiconducting SWCNTs possess high charge carrier mobilities, rendering them well-suited for memory and logic devices.
(2) Mechanical properties: SWCNTs are low weight, high tensile strength, and high resiliency materials.
(3) Optical properties: Semiconducting SWCNTs are strong absorbers and emitters of light in the near-infrared portion of the electromagnetic spectrum, which is useful for fiber optic communication and biomedical imaging. Metallic SWCNTs are relatively transparent in the visible portion of the spectrum, which allows their use in transparent conductor applications such as flat panel displays and solar cells.
(4) Thermal properties: SWCNTs possess high thermal conductivity and high thermal stability. In particular, SWCNTs can sustain temperatures of ~700�C in air and ~2800�C in vacuum.
(5) Chemical properties: SWCNTs can be covalently or noncovalently functionalized with a variety of molecules and materials including nanoparticles, DNA, proteins, and polymers. This chemical flexibility enables their use in a variety of applications including sensors and catalysis.

Limitations in SWCNT manufacturing, however, have prevented these materials from being used to their full potential. Current SWCNT production methods generate mixtures of structurally polydisperse nanotubes (as-synthesized SWCNTs naturally vary in their diameter and chiral angle). This polydispersity is problematic because the properties of SWCNTs are sensitively determined by their physical structure. Thus, although SWCNTs can presently be produced in large volumes, the heterogeneity of as-synthesized SWCNTs has precluded their widespread use.

Before serious SWCNT-based product development can occur, a method for producing large volumes of SWCNTs that are monodisperse in their diameter, bandgap, and/or electronic type must be developed. While technologies exist that can accomplish this objective on a laboratory scale (these methods generally involve separating as-synthesized, polydisperse SWCNTs), no such technology has been proven to be sufficiently scalable or economical to produce large volumes of SWCNTs that are monodisperse in their structure and properties.

PHASE I: Assess all available techniques for producing monodisperse populations of SWCNTs to determine which method is most scalable and economical. Create a detailed plan for building and testing a setup to produce and characterize large volumes of SWCNTs that are monodisperse in their diameter, bandgap, and/or electronic type. This phase may be accomplished both through experimentation and theoretical analysis.

PHASE II: Develop and demonstrate a prototype production setup that can generate and characterize large volumes of SWCNTs that are monodisperse in their diameter, bandgap, and/or electronic type. Quantify relevant commercial figures of merit including throughput, yield, purity, and cost.

PHASE III: Given their unique properties, monodisperse SWCNTs can potentially be incorporated into a broad range of devices, such as transparent conductive films for displays and solar panels, interconnects in integrated circuits, high-performance field-effect transistors, thin-film transistors, near-infrared emitters and detectors, and biosensors. In such devices, SWCNTs offer advantages over competing materials. Most notably, semiconducting SWCNTs display greater charge carrier mobility than crystalline silicon, metallic SWCNTs can withstand higher current densities than copper, and SWCNT films are more physically resilient than metal-oxide films. The durability and performance of thin-film SWCNT devices make them particularly well-suited for military and civilian applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Given their unique properties, monodisperse SWCNTs can potentially be incorporated into a broad range of devices, such as transparent conductive films for displays and solar panels, interconnects in integrated circuits, high-performance field-effect transistors, thin-film transistors, near-infrared emitters and detectors, and biosensors. In such devices, SWCNTs offer advantages over competing materials. Most notably, semiconducting SWCNTs display greater charge carrier mobility than crystalline silicon, metallic SWCNTs can withstand higher current densities than copper, and SWCNT films are more physically resilient than metal-oxide films. The durability and performance of thin-film SWCNT devices make them particularly well-suited for military and civilian applications.

REFERENCES:
1. Baughman RH, Zakhidov AA, de Heer WA, Carbon nanotubes - the route toward applications, SCIENCE 297 (5582): 787-792 AUG 2 2002

2. Collins PG, Avouris P, Nanotubes for electronics , SCIENTIFIC AMERICAN 283 (6): 62-69 DEC 2000

3. Haddon RC, Sippel J, Rinzler AG, et al., Purification and separation of carbon nanotubes, MRS BULLETIN 29 (4): 252-259 APR 2004

4. Krupke R, Hennrich F, von Lohneysen H, et al., Separation of metallic from semiconducting single-walled carbon nanotubes, SCIENCE 301 (5631): 344-347 JUL 18 2003

5. Strano MS, Dyke CA, Usrey ML, et al., Electronic structure control of single-walled carbon nanotube functionalization, SCIENCE 301 (5639): 1519-1522 SEP 12 2003

6. Zheng M, Jagota A, Strano MS, et al., Structure-based carbon nanotube sorting by sequence-dependent DNA assembly, SCIENCE 302 (5650): 1545-1548 NOV 28 2003

7. Heller DA, Mayrhofer RM, Baik S, et al., Concomitant length and diameter separation of single-walled carbon nanotubes, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 126 (44): 14567-14573 NOV 10 2004

8. Arnold MS, Stupp SI, Hersam MC, Enrichment of single-walled carbon nanotubes by diameter in density gradients, NANO LETTERS 5 (4): 713-718 APR 2005

9. Arnold MS, Green AA, Hersam MC, et al., Sorting carbon nanotubes by electronic structure using density differentiation, NATURE NANOTECHNOLOGY 1 (1): 60-65 OCT 2006

KEYWORDS: Carbon nanotubes, single-walled carbon nanotubes, monodisperse, metallic, semiconducting, bandgap, transistors, sensors, near-infrared, detectors, transparent conductors.

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 12 and December 7, 2008, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 8, 2008, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (09.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 09.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 or email weblink.