Electrical and thermal properties of alloys of CdTe and CdSe

The CdTe:CdSe system has been investigated in order to assess its thermoelectric properties. A series of alloys was made ranging from 10 mol.% CdSe in CdTe to 30:70 CdTe:CdSe. Those containing up to 30 mol.% CdSe were found to have a zinc blende structure while the 30:70 CdTe:CdSe alloy had a wurtzite structure. At the equimolecular composition the structure was dominantly cubic but converted to hexagonal on doping with iodine. The material was of small grain size, extremely brittle, and thermally unstable above 250°C. A wide variation in electrical conductivity (from 54 to 740 (Ωcm)−1) was found, giving rise to a large spread in mobility, which was probably due to the poor structure of the material. Measurements of electrical conductivity, Hall constant, thermoelectric power and thermal conductivity were carried out above room temperature, within the limits of thermal stability. Thermoelectric power decreased with increasing CdSe content and increased linearly with increasing temperature up to 400°C. Thermoelectric figures of merit were a little greater than for iodine doped CdTe, the best achieved being that for the 70:30 CdTe:CdSe alloy.