Carbon nanotubes: optimized growth for applications and practical use of large CNT structures :Carbon nanotubes: optimized growth for applications and practical use of large CNT structures Robert Vajtai*, G. Toth, K. Kordas, X. H. An, P. M. Ajayan* *Department of Mechanical Engineering & Materials Science Rice University, Houston, Texas


Outline :Very short introduction Carbon nanotube forest: the materials we deal with Experimental setup/Results on cooling: measurements and calculations Printed electronics made of carbon nanotubes Conclusions Outline


Introduction :Introduction Carbon nanotubes are well-studied scientifically They have unique physical properties Real life applications are still hiding, waiting CNTs are not industrially used because of technological and economical reasons


Outline :Introduction Carbon nanotube forest: the materials we deal with Experimental setup/Results on cooling: measurements and calculations Printed electronics made of carbon nanotubes Conclusions Outline


Experimental setup for CVD :Experimental setup for CVD Substrates: Si, SiO2, MgO, V2O5Precursors: methane, ethylene, xylene Catalysts: Fe from ferrocene, Ni, Pd, Co-Ni


Slide 6:Thin(?) film of aligned nanotubes


Slide 7:Growth rate: 1 mm/hr Area: 8 x 2.5 cm2 Number of tubes: 8 x 1011 (800 billion) Film density: 0.17 g/cm3 (calculated) 0.16 g/cm3 (measured) Geometric properties of the film Fe content: 7.8% (weight) Prof. Cao


Saturation in length and larger diameter :Saturation in length and larger diameter 30 min 120 min 300 min 600 min Dr. Li


Longer tubes… :Longer tubes…


Even longer tubes… :Even longer tubes…


Inconel also works as a substrate :Inconel also works as a substrate S. Talapatra, R. Vajtai, P.M. Ajayan et al. Nature Nanotechnology, 1(2) 112–116 (2006)


Well :Well


Growth kinetics :Growth kinetics N. Halonen, K. Kordás, G. Tóth, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008)


Growth kinetics :Growth kinetics N. Halonen, K. Kordás, G. Tóth, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008)


Growth kinetics :Growth kinetics N. Halonen, K. Kordás, G. Tóth, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008)


Growth kinetics :Growth kinetics N. Halonen, K. Kordás, G. Tóth, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008)


Growth kinetics :Growth kinetics N. Halonen, K. Kordás, G. Tóth, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008)


Outline :Introduction Carbon nanotube forest: the materials we deal with Experimental setup/Results on cooling: measurements and calculations Printed electronics made of carbon nanotubes Conclusions Outline


Chip cooling: problem to solve :Chip cooling: problem to solve Chip cooling is necessary Present methods do not work (sufficiently) CNTs are promising materials Still there are open scientific and engineering questions


Preparation of the finned structure :Preparation of the finned structure K. Kordás, G. Tóth, R. Vajtai, P. M. Ajayan et al., Appl. Phys. Lett. 90, 123105 (2007)


Mounting the cooler device :Mounting the cooler device K. Kordás, G. Tóth, R. Vajtai, P. M. Ajayan et al., Appl. Phys. Lett. 90, 123105 (2007)


Experimental results :Experimental results Without coolant gas: ~0.3 W removed 30 W/cm2 ~1 kW/g nanotube With 2 l/min gas: ~1.1 W removed >100 W/cm2 >1 kW/g nanotube


Comparison to copper :Comparison to copper K. Kordás, G. Tóth, R. Vajtai, P. M. Ajayan et al., Appl. Phys. Lett. 90, 123105 (2007)


Cooler: Summary of properties :Cooler: Summary of properties The cooler increases surface area “intelligently” Can be mounted on Device Heat Spreader Active cooler Passive cooler No CTE matching problems occur Mechanically stabile in the 10-100 µm range, too Variable shapes are easy to grow and manufacture The structure has very small weight (several ten times less than similar sized metal structures)


Outline :Introduction Carbon nanotube forest: the materials we deal with Experimental setup/Results on cooling: measurements and calculations Printed electronics made of carbon nanotubes Conclusions Outline


Ink preparation :Ink preparation K. Kordás, G. Tóth, S. Kar, R. Vajtai, P. M. Ajayan et al., Small 2, 1021 (2006)


Slide 27:Nanotube Structures Printed on Paper The printed structure can be a flexible antenna or simply a wire to connect electrical parts K. Kordás, G. Tóth, S. Kar, R. Vajtai, P. M. Ajayan et al., Small 2, 1021 (2006)


Printing results on alumina template :Printing results on alumina template T. Mustonen, K. Kordás, G. Tóth, P. M. Ajayan, R. Vajtai et al., Phys. Rev. B 77, 125430 (2008)


Slide 29:Printing results on alumina template


Silicon substrate: results :Silicon substrate: results


Sensor properties :Sensor properties


Outline :Introduction Carbon nanotube forest: the materials we deal with Experimental setup/Results on cooling: measurements and calculations Printed electronics made of carbon nanotubes Conclusions Outline


Conclusions :Conclusions Large carbon nanotube structures have application potential They have unique synergetic thermal and electrical properties Large amount of nanotubes is not more expensive; on the contrary, it can be more economic to deal with them than building devices from individual CNTs


Acknowledgements :Acknowledgements Profs. T. Borca-Tasciuc, S. Talapatra, A.Y. Cao Drs. S. Pal, L. Ci, X. Li Interconnect Focus Center, NYSTAR NSEC (DMR-0642573)


Slide 35:Thanks to the organizers for the invitation THANK YOU for your attention Please feel free to contact me for more information:Robert.Vajtai at rice.edu