Thermoelectric properties of Ga-doped InSb alloys

Internal structure and thermoelectric properties of In1-xGaxSb alloys, prepared by melting synthesis at 1123 K, were systematically studied in this paper. Crystal structure was investigated by XRD analysis. All samples exhibited crystalline structure of single InSb phase. Transport and electrical properties were studied against temperature elevating. Electrical conductivity was determined via the standard four probe method. The thermal behavior of the electrical conductivity over the temperature range between 273 K and 473 K showed semiconducting behavior. Seebeck coefficient measurements were conducted via differential method in the temperature range 273–473 K. The measurements of Seebeck coefficient confirmed the electrical conductivity behavior of the samples. The maximum obtained Seebeck coefficient value |S| of the parent InSb compound was observed at 224 μV/K, obtained at 273 K. The alloy has been doped with Ga in order to enhance thermoelectric properties. Results showed that introducing of Ga into In sites leads to significant increase in the Seebeck coefficient up to 330.4 μV/K. Power factor was estimated from the measurements of the electrical conductivity and the Seebeck coefficient. Interesting enhancement in the thermoelectric power factor was observed with Ga-doping. The maximum power factor was obtained for the most doped sample exhibiting 2.3 μWm−1 K−2 at 273 K. The thermal conductivity was obviously reduced by substituting In with Ga. The dimensionless figure of merit was estimated showing an enhancement with the Ga addition. The maximum recorded ZT was 0.017 observed at 403 K.