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

Abstract

The electrical resistivity, ρ, was measured for the melt of a typical III-V semiconductor system, Ga-Sb, by the direct-current four-probe method. Similarly to the case for solid substitutional alloys, the Nordheim rule almost establishes the concentration dependence of ρ. That is, a rather parabolic form of ρ was obtained as a function of composition; ρ is the deviation of the resistivity from the linear law relating the resistivities of the pure components, liquid Ga and liquid Sb. In spite of this rather simple behaviour of the concentration dependence of ρ itself, its temperature coefficient, dρ/dT , shows a clear minimum at the eutectic composition and even a negative temperature coefficient was observed near the eutectic point. This negative dρ/dT may be the first indication for the existence of particular hidden structure, related to concentration fluctuations, in the liquid near the eutectic point. In addition, this strange behaviour of dρ/dT was discussed on the basis of the effective-medium theory.

The estimation of concentration fluctuations in liquid Ag–Si and Au–Si alloys

“…The deviation of specific electrical resistivity for liquid Au-Si alloys shows a maximum also at the eutectic composition. Similar maximum of deviation at the eutectic composition has been found also for liquid Ga-Sb [3,4], In-Sb [4], Ag-Ge [8] and Au-Ge [8] alloys, in which a minimum of the temperature coefficient of specific electrical resistivity also exists at the eutectic composition. Therefore, the homogeneous liquids at the eutectic composition for Ag-Si and Au-Si systems show an anomalous behavior derived from the concentration fluctuations.…”

“…The measurements of specific electrical rsistivity and its temperature coefficient were performed with an error within ± 0.5 % and 0.0005 μΩcmK ± -1 respectively judging from the reproducibility of measurements. These error bars are almost same as those in previous similar studies for liquid eutectic alloys [3,4,8].…”

“…This fact was found based on the change of the sign of the temperature coefficient of specific electrical resistivity [3]. For liquid Ga 11.8 -Sb 88.2 (eutectic composition), the specific electrical resistivity decreased on lowering the temperature from 1200 K to 920 K; this behavior is metallic due to a positive temperature coefficient.…”

“…In previous papers [3,4,8], we have revealed that with the approach to the eutectic temperature in the homogeneous liquid phase, the concentration fluctuations appear around the eutectic composition. This fact was found based on the change of the sign of the temperature coefficient of specific electrical resistivity [3].…”

“…The Ar gas purge enabled us to keep the O 2 concentration of furnace atmosphere low. The U type cell, whose design was described elsewhere [3], was composed of a capillary part (a), two quarts tubes (b) as a sample reservoir part (which is connected by the capillary part (a) like U shape), and sample inlet port (c). Two W electrodes and the small glass tube (d) were inserted into two quarts tubes (b) in terms of the graphite plug.…”