Thermoelectric Properties of Mg₂Si_0.6Ge_0.4

Abstract

Mg₂Si_0.6Ge_0.4 solid solution semiconductor was prepared by direct melting, where the reaction between samples and graphite crucible was suppressed using NaCl flux. Carrier concentrations were controlled in the regions of 6.5×10²⁴∼1.5×10²⁶ electrons/m³ and 1.0×10²⁴∼5.5×10²⁵ holes/m³ by doping Sb and Ag, respectively. Thermal conductivity k was measured at 300 K for Sb-doped samples. By calculating the electronic thermal conductivity k_el based on the Fermi integrailon, the lattice thermal conductivity k_ph was estimated to be 2.10 Wm⁻¹K⁻¹. Figure-of-merits Z, of Mg₂Si_0.6Ge_0.4 at 300 K were 0.69×10⁻³ K⁻¹ for the n-type sample with an electron concentration of 5.4×10²⁵ m⁻³ (3000 ppm Sb) and 0.47×10⁻³ K⁻¹ for p-type one with a hole concentration of 5.2×10²⁵ m⁻³ (16000 ppm Ag).