THERMOELECTRIC-POWER OF SOME COMPOSITIONS OF GETE-RICH (GETE)1-X(AGBITE2)X SOLID-SOLUTIONS

A method for preparing single-phase ingots of GeTe-rich solid solutions (x less-than-or-equal-to 0.20) in the system (GeTe)1-x(AgBiTe2)x is developed. The temperature dependence (77 to congruent-to 900 K) of the thermoelectric power is measured. The curves for GeTe and GeTe-rich solid solutions are of similar shape. Using conventional transport theory, the lattice and electronic contributions to this effect are obtained. To explain the behaviour of diffusion and phonon-drag terms, the metallic expressions for both are used. On the basis of band-edge models of GeTe and AgBiTe2, the non-parabolic two-band Kane model of IV-VI compounds, and separate values of the electronic parts of the thermoelectric power, information about the Fermi energy and degree of degeneracy is obtained. A qualitative interpretation of the temperature dependence of S(e) is made.