Phonon scattering by charge carriers and impurities reduces the thermal conductivity in heavily doped semiconductors, but understanding of the respective roles of these mechanisms is still lacking, as previous works arrived at apparently contradicting conclusions regarding the dominant reduction mechanism. In this work, we study the thermal conductivity of P- and B-doped silicon experimentally with the $3\omega$ method, as well as with predictive density-functional-theory-based calculations. Our work offers a generalized picture of two distinct heat-transport reduction regimes: one due to charge-carrier scattering and another due to impurity scattering, which depend on temperature, doping concentration, and the size of the heat source. We further propose a simple concentration-dependent thermal conductivity reduction model, which demonstrates that the two reduction regimes can be clearly distinguished by different exponential stretching. Our findings reconcile the claims of previous works and can be applied to other doped semiconductors.

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• Doping effects
• Electron-phonon coupling
• Thermal transport
• Doped semiconductors
• Electrical transport techniques
• First-principles calculations