Publications

2026

• Competing effects of charge-carrier and impurity scattering limiting phonon heat conduction in heavily-doped silicon
  
  • Sen Raja
  • Acosta Abanto Juan Carlos
  • Brouillard Mélanie
  • Gomès Séverine
  • Robillard Jean-François
  • Ciavatta Alessandro
  • Paulatto Lorenzo
  • Vast Nathalie
  • Saint-Martin Jérôme
  • Sjakste Jelena
  • Chapuis Pierre-Olivier
  , 2026. With respect to undoped semiconductors, thermal transport by phonons is limited by two additional mechanisms when doping increases: charge-carrier and impurity scattering. Previous works provided contradicting conclusions on the dominant doping-induced scattering mechanism in silicon. In this work, we clarify the competing roles of impurity and charge-carrier scatterings of phonons in the reduction of the lattice thermal conductivity in n-and p-doped silicon, by comparing experimental results obtained with the 3ω method and predictive DFT-based calculations for a large set of doping concentrations and a wide temperature range. The analysis allows delimiting the doping and temperature ranges where (i) extrinsic scattering surpasses intrinsic (phonon-phonon and phonon-isotope) one and (ii) one of the two doping-induced mechanisms plays the dominant role. We observe that the experimental setup impacts both the thermal conductivity value and the critical doping concentration at which the thermal conductivity is reduced by half.
• Static and dynamic Monte Carlo simulations of phonon drag effects on thermoelectric properties in silicon nanostructures
  
  • Ghanem Mohammad
  • Dollfus Philippe
  • Sen Raja
  • Sjakste Jelena
  • Saint-Martin Jérôme
  , 2026. Thermoelectric transport in silicon nanofilms is investigated using a self-consistent electro-thermal Monte Carlo simulator that couples electron dynamics to a phonon bath with spatially varying temperature. A key novelty of this work is the explicit inclusion of the phonon-drag contribution, implemented by modifying the electron-phonon momentum exchange based on the local deviation of the phonon distribution from equilibrium. The method is validated against bulk silicon data and extended to incorporate rough boundary scattering for both electrons and phonons, yielding excellent agreement with experimental measurements on nanofilms. We also analyze the transient regime and show that a temperature bias produces a slower current response than a voltage bias, although the phonon-drag effect itself tends to accelerate the response. These results demonstrate that the proposed framework provides a powerful tool for predicting both steady-state and time-dependent thermoelectric behavior in semiconductor nanostructures.