Thermoelectric properties of Ge_(1-x)Sn_xTe crystals grown by vertical Bridgman method

摘要

Single crystals of Ge_(1-x)Sn_xTe 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 Ge_(1-x)Sn_xTe 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 Ge_(1-x)Sn_xTe were analyzed. A two-valence band model was proposed to describe the temperature dependence of thermoelectric property of the Ge_(1-x)Sn_xTe crystals. The dimensionless thermoelectric figure of merit ZT for the alloys was evaluated and discussed.