Abstract
Approximately 90 per cent of the world’s power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30–40 per cent efficiency, such that roughly 15 terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT > 1, since the parameters of ZT are generally interdependent1. While nanostructured thermoelectric materials can increase ZT > 1 (refs 2–4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20–300 nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50 nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.
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References
Majumdar, A. Thermoelectricity in semiconductor nanostructures. Science 303, 777–778 (2004)
Hsu, K. F. et al. Cubic AgPbmSbTe2+m: bulk thermoelectric materials with high figure of merit. Science 303, 818–821 (2004)
Harman, T. C., Taylor, P. J., Walsh, M. P. & LaForge, B. E. Quantum dot superlattice thermoelectric materials and devices. Science 297, 2229–2232 (2002)
Venkatasubramanian, R., Siivola, E., Colpitts, T. & O’Quinn, B. Thin-film thermoelectric devices with high room-temperature figures of merit. Nature 413, 597–602 (2001)
Touloukian, Y. S., Powell, R. W., Ho, C. Y. & Klemens, P. G. Thermal Conductivity: Metallic Elements and Alloys, Thermophysical Properties of Matter Vol. 1 339 (IFI/Plenum, New York, 1970)
Weber, L. & Gmelin, E. Transport properties of silicon. Appl. Phys. A 53, 136–140 (1991)
Nolas, G. S., Sharp, J. & Goldsmid, H. J. in Thermoelectrics: Basic Principles and New Materials Development (eds Nolas, G. S., Sharp, J. & Goldsmid, H. J.) Ch. 3 (Springer, Berlin, 2001)
Asheghi, M., Leung, Y. K., Wong, S. S. & Goodson, K. E. Phonon-boundary scattering in thin silicon layers. Appl. Phys. Lett. 71, 1798–1800 (1997)
Asheghi, M., Touzelbaev, M. N., Goodson, K. E., Leung, Y. K. & Wong, S. S. Temperature-dependent thermal conductivity of single-crystal silicon layers in SOI substrates. J. Heat Transf. 120, 30–36 (1998)
Ju, Y. S. & Goodson, K. E. Phonon scattering in silicon films with thickness of order 100 nm. Appl. Phys. Lett. 74, 3005–3007 (1999)
Peng, K. Q., Yan, Y. J., Gao, S. P. & Zhu, J. Synthesis of large-area silicon nanowire arrays via self-assembling nanochemistry. Adv. Mater. 14, 1164–1167 (2002)
Peng, K., Yan, Y., Gao, S. & Zhu, J. Dendrite-assisted growth of silicon nanowires in electroless metal deposition. Adv. Funct. Mater. 13, 127–132 (2003)
Peng, K. et al. Uniform, axial-orientation alignment of one-dimensional single-crystal silicon nanostructure arrays. Angew. Chem. Intl Edn. 44, 2737–2742 (2005)
Li, D. et al. Thermal conductivity of individual silicon nanowires. Appl. Phys. Lett. 83, 2934–2936 (2003)
Hochbaum, A. I., Fan, R., He, R. & Yang, P. Controlled growth of Si nanowire arrays for device integration. Nano Lett. 5, 457–460 (2005)
Ashcroft, N. W. & Mermin, N. D. Solid State Physics Chs 1, 2 and 13 (Saunders College Publishing, Fort Worth, 1976)
Sze, S. M. Physics of Semiconductor Devices Ch. 1 (John Wiley & Sons, New York, 1981)
Shi, L. et al. Measuring thermal and thermoelectric properties of one-dimensional nanostructures using a microfabricated device. J. Heat Transf. 125, 881–888 (2003)
Kim, W. et al. Thermal conductivity reduction and thermoelectric figure of merit increase by embedding nanoparticles in crystalline semiconductors. Phys. Rev. Lett. 96, 045901 (2006)
Zou, J. & Balandin, A. Phonon heat conduction in a semiconductor nanowire. J. Appl. Phys. 89, 2932–2938 (2001)
Saha, S., Shi, L. & Prasher, R. Monte Carlo simulation of phonon backscattering in a nanowire. Proc. ASME Int. Mech. Eng. Congr. Exp. (5–10 November 2006) art. no. 15668 1–5 (ASME, Chicago, 2006)
Rowe, D. M. CRC Handbook of Thermoelectrics Ch. 5 (CRC Press, Boca Raton, 1995)
Brinson, M. E. & Dunstan, W. Thermal conductivity and thermoelectric power of heavily doped n-type silicon. J. Phys. C 3, 483–491 (1970)
Ruf, T. et al. Thermal conductivity of isotopically enriched silicon. Solid State Commun. 115, 243–247 (2000)
Cahill, D. G. & Pohl, R. O. Thermal conductivity of amorphous solids above the plateau. Phys. Rev. B 35, 4067–4073 (1987)
Cahill, D. G., Watson, S. K. & Pohl, R. O. Lower limit to the thermal conductivity of disordered crystals. Phys. Rev. B 46, 6131–6140 (1992)
Mingo, N., Yang, L., Li, D. & Majumdar, A. Predicting the thermal conductivity of Si and Ge nanowires. Nano Lett. 3, 1713–1716 (2003)
Acknowledgements
We thank T.-J. King-Liu and C. Hu for discussions and J. Goldberger for TEM analysis. We acknowledge the support of the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, DOE. A.I.H. and R.C. thank the NSF-IGERT and ITRI-Taiwan programs, respectively, for fellowship support. We also thank the National Center for Electron Microscopy and the UC Berkeley Microlab for the use of their facilities. R.D.D. thanks the GenCat/Fulbright programme for support.
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Hochbaum, A., Chen, R., Delgado, R. et al. Enhanced thermoelectric performance of rough silicon nanowires. Nature 451, 163–167 (2008). https://doi.org/10.1038/nature06381
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DOI: https://doi.org/10.1038/nature06381
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