Thermoelectric properties of Ge1−xSnxTe crystals grown by vertical Bridgman method

Single crystals of Ge1−xSnxTe compounds with x=0, 0.8, 0.9 and 1.0 were grown by vertical Bridgman method. The crystalline phase and stochiometry for these crystals were investigated by X-ray diffraction, metallographic microscope as well as electron-probe microanalysis (EPMA). Electrical property of the as-grown samples was characterized using room temperature resistivity and Hall measurements. The thermoelectric behaviors for the Ge1−xSnxTe crystals were studied by means of thermal and carrier transport measurements. Temperature dependences of resistivity, Seebeck coefficient and thermal conductivity for the various compositions of Ge1−xSnxTe were analyzed. A two-valence band model was proposed to describe the temperature dependence of thermoelectric property of the Ge1−xSnxTe crystals. The dimensionless thermoelectric figure of merit ZT for the alloys was evaluated and discussed.