Effects of crystal orientation, temperature, and molten zone thickness in temperature-gradient zone-melting

Abstract

A strong orientation effect has been found for molten aluminum-rich wire zones traversing single crystals of germanium. If the intersection of a {111} plane with the plane of wire-travel is oblique to the wire, the wire breaks into segments that lie parallel to the line of intersection. However, if the line of intersection is perpendicular or parallel to the wire, the wire remains straight. This crystalline anisotrophy has been utilized to make highly parallel npn junctions using aluminum-rich wire zones in germanium. The rate of zone movement increases unusually rapidly with temperature and with diameter of the wire zone. These findings suggest that the rate-controlling factor in these experiments is not diffusion in the liquid zone, but the solution rate at the hotter interface. Diffusion may become the limiting process at higher temperatures and lower temperature gradients.