Induced Electric Fields In Anisotropic Thermoelectric Materials

Transport in an anisotropic material can create potentially large induced transverse fields which reduce the measured electric and thermal conductivities relative to those computed without the induced fields. These affect the thermoelectric figure of merit ZT modestly. The induced electric field in n-type Bi2Te3 is predicted to be as much as 76% of the external one and can lower the measured electrical conductivity by up to 60%. In Hg1-xCdxTe superlattices, the anisotropy may be increased by varying the composition and width of the barrier and well to give induced fields much larger than the applied one. These effects should be easily observable. The present work utilizes general results applied to a microscopic model relevant for multivalleyed materials within the effective-mass and relaxation-time approximations. (C) 1999 American Institute of Physics. [S0021-8979(99)05521-8].