Nano Research

, Volume 8, Issue 9, pp 2833–2841 | Cite as

Tailoring thermal conductivity by engineering compositional gradients in Si1−x Ge x superlattices

  • Pablo Ferrando-Villalba
  • Aitor F. Lopeandía
  • Francesc Xavier Alvarez
  • Biplab Paul
  • Carla de Tomás
  • Maria Isabel Alonso
  • Miquel Garriga
  • Alejandro R. Goñi
  • Jose Santiso
  • Gemma Garcia
  • Javier Rodriguez-Viejo
Research Article


The transport properties of artificially engineered superlattices (SLs) can be tailored by incorporating a high density of interfaces in them. Specifically, SiGe SLs with low thermal conductivity values have great potential for thermoelectric generation and nano-cooling of Si-based devices. Here, we present a novel approach for customizing thermal transport across nanostructures by fabricating Si/Si1−x Ge x SLs with well-defined compositional gradients across the SiGe layer from x = 0 to 0.60. We demonstrate that the spatial inhomogeneity of the structure has a remarkable effect on the heat-flow propagation, reducing the thermal conductivity to ∼2.2 W·m−1·K−1, which is significantly less than the values achieved previously with non-optimized long-period SLs. This approach offers further possibilities for future applications in thermoelectricity.


SiGe superlattices thermal conductivity composition gradients heat transport 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Wang, Z. L. Energy harvesting for self-powered nanosystems. Nano Res. 2008, 1, 1–8.CrossRefGoogle Scholar
  2. [2]
    Zhao, L. D.; Wu, H. J.; Hao, S. Q.; Wu, C. I.; Zhou, X. Y.; Biswas, K.; He, J. Q.; Hogan, T. P.; Uher, C.; Wolverton, C. et al. All-scale hierarchical thermoelectrics: MgTe in PbTe facilitates valence band convergence and suppresses bipolar thermal transport for high performance. Energy Environ. Sci. 2013, 6, 3346–3355.CrossRefGoogle Scholar
  3. [3]
    Balasubramanian, G.; Puri, I. K.; Böhm, M. C.; Leroy, F. Thermal conductivity reduction through isotope substitution in nanomaterials: Predictions from an analytical classical model and nonequilibrium molecular dynamics simulations. Nanoscale 2011, 3, 3714–3720.CrossRefGoogle Scholar
  4. [4]
    Zhang, G.; Li, B. W. Impacts of doping on thermal and thermoelectric properties of nanomaterials. Nanoscale 2010, 2, 1058–1068.CrossRefGoogle Scholar
  5. [5]
    Pop, E. Energy dissipation and transport in nanoscale devices. Nano Res. 2010, 3, 147–169.CrossRefGoogle Scholar
  6. [6]
    Rowe, D. M.; Fu, L. W.; Williams, S. G. K. Comments on the thermoelectric properties of pressure-sintered Si0.8Ge0.2 thermoelectric alloys. J. Appl. Phys. 1993, 73, 4683–4685.CrossRefGoogle Scholar
  7. [7]
    Joshi, G.; Lee, H.; Lan, Y. C.; Wang, X. W.; Zhu, G. H.; Wang, D. Z.; Gould, R. W.; Cuff, D. C.; Tang, M. Y.; Dresselhaus, M. S. et al. Enhanced thermoelectric figure-of-merit in nanostructured p-type silicon germanium bulk alloys. Nano Lett. 2008, 8, 4670–4674.CrossRefGoogle Scholar
  8. [8]
    Lee, S. M.; Cahill, D. G.; Venkatasubramanian, R. Thermal conductivity of Si-Ge superlattices. Appl. Phys. Lett. 1997, 70, 2957–2959.CrossRefGoogle Scholar
  9. [9]
    Borca-Tasciuc, T.; Liu, W.; Liu, J. L.; Zeng, T. F.; Song, D. W.; Moore, C. D.; Chen, G.; Wang, K. L.; Goorsky, M. S.; Radetic, T. et al. Thermal conductivity of symmetrically strained Si/Ge superlattices. Superlattice. Microst. 2000, 28, 199–206.CrossRefGoogle Scholar
  10. [10]
    Huxtable, S. T.; Abramson, A. R.; Tien, C. L.; Majumdar, A.; LaBounty, C.; Fan, X.; Zeng, G. H.; Bowers, J. E.; Shakouri, A.; Croke, E. T. Thermal conductivity of Si/SiGe and SiGe/SiGe superlattices. Appl. Phys. Lett. 2002, 80, 1737–1739.CrossRefGoogle Scholar
  11. [11]
    Chakraborty, S.; Kleint, C. A.; Heinrich, A.; Schneider, C. M.; Schumann, J.; Falke, M.; Teichert, S. Thermal conductivity in strain symmetrized Si/Ge superlattices on Si(111). Appl. Phys. Lett. 2003, 83, 4184–4186.CrossRefGoogle Scholar
  12. [12]
    Liu, C. K.; Yu, C. K.; Chien, H. C.; Kuo, S. L.; Hsu, C. Y.; Dai, M. J.; Luo, L. G.; Huang, S. C.; Huang, M. J. Thermal conductivity of Si/SiGe superlattice films. J. Appl. Phys. 2008, 104, 114301.CrossRefGoogle Scholar
  13. [13]
    Pernot, G.; Stoffel, M.; Savic, I.; Pezzoli, F.; Chen, P.; Savelli, G.; Jacquot, A.; Schumann, J.; Denker, U.; Moench, I. et al. Precise control of thermal conductivity at the nanoscale through individual phonon-scattering barriers. Nat. Mater. 2010, 9, 491–495.CrossRefGoogle Scholar
  14. [14]
    Chen, P. X.; Katcho, N. A.; Feser, J. P.; Li, W.; Glaser, M.; Schmidt, O. G.; Cahill, D. G.; Mingo, N.; Rastelli, A. Role of surface-segregation-driven intermixing on the thermal transport through planar Si/Ge superlattices. Phys. Rev. Lett. 2013, 111, 115901.CrossRefGoogle Scholar
  15. [15]
    Liu, J. L.; Khitun, A; Wang, K. L.; Liu, W. L.; Chen, G.; Xie, Q. H.; Thomas, S. G. Cross-plane thermal conductivity of self-assembled Ge quantum dot superlattices. Phys. Rev. B 2003, 67, 165333.CrossRefGoogle Scholar
  16. [16]
    Alvarez-Quintana, J.; Alvarez, X.; Rodriguez-Viejo, J.; Jou, D.; Lacharmoise, P. D.; Bernardi, A.; Goñi, A. R.; Alonso, M. I. Cross-plane thermal conductivity reduction of vertically uncorrelated Ge/Si quantum dot superlattices. Appl. Phys. Lett. 2008, 93, 013112.CrossRefGoogle Scholar
  17. [17]
    Chang, H. T.; Wang, S. Y.; Lee, S. W. Designer Ge/Si composite quantum dots with enhanced thermoelectric properties. Nanoscale 2014, 6, 3593–3598.CrossRefGoogle Scholar
  18. [18]
    Cecchi, S.; Etzelstorfer, T.; Müller, E.; Samarelli, A.; Llin, L. F.; Chrastina, D.; Isella, G.; Stangl, J.; Paul, D. J. Ge/SiGe superlattices for thermoelectric energy conversion devices. J. Mater. Sci. 2013, 48, 2829–2835.CrossRefGoogle Scholar
  19. [19]
    Samarelli, A.; Llin, L. F.; Cecchi, S.; Frigerio, J.; Etzelstorfer, T.; Mueller, E.; Zhang, Y.; Watling, J. R.; Chrastina, D.; Isella, G. et al. The thermoelectric properties of Ge/SiGe modulation doped superlattices. J. Appl. Phys. 2013, 113, 233704.CrossRefGoogle Scholar
  20. [20]
    Kiselev, A. A.; Kim, K. W.; Stroscio, M. A. Thermal conductivity of Si/Ge superlattices: A realistic model with a diatomic unit cell. Phys. Rev. B 2000, 62, 6896–6899.CrossRefGoogle Scholar
  21. [21]
    Broido, D. A.; Reinecke, T. L. Lattice thermal conductivity of superlattice structures. Phys. Rev. B 2004, 70, 081310.CrossRefGoogle Scholar
  22. [22]
    Garg, J.; Bonini N.; Marzari N. High thermal conductivity in short-period superlattices. Nano Lett. 2011, 11, 5135–5141.CrossRefGoogle Scholar
  23. [23]
    Savic, I.; Donadio, D.; Gyg, F.; Galli, G. Dimensionality and heat transport in Si-Ge superlattices. Appl. Phys. Lett. 2013, 102, 073113.CrossRefGoogle Scholar
  24. [24]
    Alvarez, F. X.; Alvarez-Quintana, J.; Jou, D.; Viejo, J. R. Analytical expression for thermal conductivity of superlattices. J. Appl. Phys. 2010, 107, 084303.CrossRefGoogle Scholar
  25. [25]
    Cheaito, R.; Duda, J. C.; Beechem, T. E.; Hattar, K.; Ihlefeld, J. F.; Medlin, D. L.; Rodriguez, M. A.; Campion, M. J.; Michael, J.; Piekos, E. S. et al. Experimental investigation of size effects on the thermal conductivity of silicon-germanium alloy thin films. Phys. Rev. Lett. 2012, 109, 195901.CrossRefGoogle Scholar
  26. [26]
    Cahill, D. G.; Fisher, H. E.; Klitsner T.; Swartz, E. T.; Pohl, R. O. Thermal conductivity of a-Si:H thin films. Phys. Rev. B 1994, 50, 6077–6081.CrossRefGoogle Scholar
  27. [27]
    Alvarez-Quintana J.; Rodríguez-Viejo J. Extension of the 3ω method to measure the thermal conductivity of thin films without a reference sample. Sensor Actuat. A 2008, 142, 232–236.CrossRefGoogle Scholar
  28. [28]
    Tong, T.; Majumdar A. Reexamining the 3-omega technique for thin film thermal characterization. Rev. Sci. Inst. 2006, 77, 104902.CrossRefGoogle Scholar
  29. [29]
    Zhylik, A.; Benediktovich, A.; Ulyanenkov, A.; Guerault, H.; Myronov, M.; Dobbie, A.; Leadley, D. R.; Ulyanenkova, T. High-resolution X-ray diffraction investigation of relaxation and dislocations in SiGe layers grown on (001), (011), and (111) Si substrates. J. Appl. Phys. 2011, 109, 123714.CrossRefGoogle Scholar
  30. [30]
    Watling, J. R.; Douglas, J. P. A study of the impact of dislocations on the thermoelectric properties of quantum wells in the Si/SiGe materials system. J. Appl. Phys. 2011, 110, 114508.CrossRefGoogle Scholar

Copyright information

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Pablo Ferrando-Villalba
    • 1
  • Aitor F. Lopeandía
    • 1
  • Francesc Xavier Alvarez
    • 2
  • Biplab Paul
    • 1
  • Carla de Tomás
    • 2
  • Maria Isabel Alonso
    • 3
  • Miquel Garriga
    • 3
  • Alejandro R. Goñi
    • 3
    • 4
  • Jose Santiso
    • 5
  • Gemma Garcia
    • 1
  • Javier Rodriguez-Viejo
    • 1
  1. 1.Grup de Nanomaterials i Microsistemes, Departament de FísicaUniversitat Autònoma de BarcelonaBellaterraSpain
  2. 2.Grup de Física Estadística, Departament de FísicaUniversitat Autònoma de BarcelonaBellaterraSpain
  3. 3.Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UABBellaterraSpain
  4. 4.ICREABarcelonaSpain
  5. 5.Institut Català de Nanociència i NanotecnologiaICN2-CSIC, Campus UABBellaterraSpain

Personalised recommendations