Thermal Conductivity, Electrical Resistivity, and Seebeck Coefficient of Silicon from 100 to 1300°K

Anisotropic failure of Fourier theory in time-domain thermoreflectance experiments

“…For TDTR measurements of Si at room temperature with w 0 o5 mm, we observe discrepancies between Fourier theory predictions and experimental data 22 , see Fig. 1.…”

BC8 Silicon (Si-III) is a Narrow-Gap Semiconductor

“…As shown in Fig. 2b, the general trend is that the modulus of the Seebeck coefficient increases with temperature with a minimum at 25-30 K. The Seebeck coefficient for BC8-Si changes from -6 µV/K at 300 K to -19 µV/K at 20 K. Comparing to DC-Si, where the Seebeck coefficient for intrinsic DC-Si is ~ -1.2 mV/K (extrapolated value from high temperature) [46,47] for polycrystalline, and ~ -440 µV/K (extrapolated value from high temperature) for single crystal samples at 300 K [46], the Seebeck coefficient of BC8-Si is much smaller, which suggests a larger mobile carrier density, consistent with the large electrical conductivity and ultra-narrow band gap feature. Additionally, the negative Seebeck coefficient suggests that electrons primarily dominate conduction, while the observed minimum could also suggest the importance of hole conduction at the lowest temperatures.…”

“…As shown in Fig. 2a, as temperature decreases, the thermal conductivity first increases from about 20-35 W/(m·K) between 300 K to 125 K, then decreases to about 7 W/(m·K) while temperature drops to 12 K. Comparing with singlecrystal [45] and polycrystalline [46] DC-Si , as shown in the inset of Fig. 2a, the thermal conductivity of the well-sintered polycrystals of BC8-Si is 1-2 orders of magnitude lower depending on the exact temperature.…”

Impact of energy filtering and carrier localization on the thermoelectric properties of granular semiconductors

“…Although this mechanism has been widely invoked to explain major improvements of the Seebeck coefficient and of the power factor, it is however considered ineffective at reverting the opposite dependency of s and a as a function of the carrier density c, so that not even in the presence of energy filtering the conductivity and the Seebeck coefficient can be expected both to grow along with c. This seemingly confirmed the opinion that the optimal value of P always occurs at some intermediate doping level. Also based upon early investigations [2,3], it was actually computed for instance that in silicon the optimal carrier density for high thermoelectric figures of merit is around 10 18 -10 19 cm À 3 [4]. This notwithstanding, interesting thermoelectric properties were experimentally anticipated for strongly degenerate silicon [5,6].…”