THERMOELECTRIC-POWER OF AMORPHOUS-ALLOYS NEAR THE METAL-INSULATOR-TRANSITION

The thermoelectric power S and the electrical conductivity a of amorph ous AuxSb100-x and CuxSb100-x films have been measured in the temperat ure range between about 2 K and 350 K for concentrations close to tile metal-insulator transition. In both systems the transition occurs at a critical concentration x(c) approximate to 8 at.% noble metal conten t. A characteristic feature of the transition is in both cases a stron g increase of the low temperature slope of the thermopower, i.e. S/T\( T --> 0), when approaching x(c), from the metallic side. The results a re compared with different theoretical predictions for the metal-insul ator transition. Furthermore we report on the changes of S and sigma d uring annealing. It will be shown that especially S(T) of the samples with x close to x(c) depends strongly on the annealing state of the fi lms.