Temperature gradient zone melting can be utilized to force metallic migration through a semiconducting wafer. The rate of metallic migration is dependent on the temperature profile within the wafer. Kellett’s model is applied to determine the temperature gradient within a radiantly heated wafer. This model includes the absorption and reradiation of energy along with strictly conductive heat transfer. Computer calculations based on the model show that the temperature gradient is constant inside the wafer and that it tends to zero near the wafer surfaces. This indicates that heat transfer is primarily by conduction inside the wafer and by radiation near the surface.