Anomalous behaviours of the electrical resistivity of the melt of a typical III-VGa-Sb system

The electrical resistivity, rho, was measured for the melt of a typical III -V semiconductor system, Ga-Sb, by the direct-current four-probe method. Si milarly to the case for solid substitutional alloys, the Nordheim rule almo st establishes the concentration dependence of rho. That is. a rather parab olic form of ap was obtained as a function of composition; Delta rho is the deviation of the resistivity from the linear law relating the resistivitie s of the pure components, liquid Ga and liquid Sb. In spite of this rather simple behaviour of the concentration dependence of rho itself, its tempera ture coefficient, d rho/dT, shows a clear minimum at the eutectic compositi on and even a negative temperature coefficient was observed near the eutect ic point. This negative d rho/dT may be the first indication for the existe nce of particular hidden structure, related to concentration fluctuations, in the liquid near the eutectic point. In addition, this strange behaviour of d rho/dT was discussed on the basis of the effective-medium theory.