Temperature gradient effect on the electromigration of Ag-Te melt inclusions in tellurium

Abstract

We have studied the electromigration (j = 5.7 × 10⁵ A/m²) of Ag-Te melt inclusions in single-crystal tellurium at an axial temperature gradient dT/dx = 1.5 × 10³ K/m. The results indicate that the movement of the inclusions is governed by the temperature gradient vector and that the penetration depth is larger in the single crystal in contact with the positive electrode. The mechanism of this effect is interpreted in terms of compositional changes in the bulk of the melt inclusions. The inclusion transport is due not only to the processes related to interfacial temperature changes under the effect of Peltier heat and the applied electric field but also to the axial temperature gradient. The additive contribution of each component has been evaluated. The velocity of melt inclusions in the bulk of the semiconductor has been shown to be size-dependent. An independent experimental procedure has been used to determine the Peltier coefficient of the interface: P _LS = − 147 mV. Using theoretical fits to experimental data, we have evaluated the kinetic solidification coefficient (β′ = 2.9 × 10⁻⁶ m/(s K)), which determines the dynamics of second phases in a gradient temperature field, and the effective charge (Z* = 0.08) and diffusion coefficient (D = 10⁻⁹ m²/s) of the semiconductor in melt inclusions.