Reductions in the thermal conductivity of irradiated silicon governed by displacement damage

We report on the measured thermal conductivity of silicon irradiated with an array of ions: ${\mathrm{C}}^{2+},$ ${\mathrm{N}}^{2+},$ ${\mathrm{Al}}^{2+},$ ${\mathrm{Si}}^{2+},$ ${\mathrm{P}}^{2+},$ and ${\mathrm{Ge}}^{2+}$. Results are analyzed in consideration of ion mass, radius, and induced displacement damage. Recrystallization of select samples via annealing demonstrates that structural disorder imparted by incident ions, rather than the ions themselves, drive the reduction in thermal conductivity. This, in turn, is dictated by the mass of the ion. A generalized model is provided to relate thermal conductivity to displacement damage. Knowledge of the displacements-per-atom profile can thus be used to predict thermal conductivity reduction for silicon devices in extreme environments.