Effect of an applied static magnetic field on silicon dissolution into a germanium melt

Abstract

An experimental investigation has been undertaken to explore the benefits of an applied static magnetic field on silicon transport into a germanium melt in a crucible configuration similar to that used in the liquid phase diffusion (LPD) and Czochralski growth systems. The measured concentration profiles with and without an applied magnetic field showed a very similar shape, while the amount of silicon transport into the melt was slightly higher in the samples processed under magnetic field. There was, however, a substantial difference in the dissolution interface shape. Without field, a flat stable interface is observed. In the presence of an applied field, the dissolution interface remains flat in the center but dramatically curves back into the source material near the wall. This indicates a far higher dissolution rate at the edges of the silicon source. It appears that the altered flow structure in the melt, due to the applied magnetic field, has increased transport at the dissolution interface near the crucible wall. In LPD growth the silicon transport is higher through the center of the melt and leads to a change in the interface shape from a concave interface towards the melt to a convex interface towards the melt at growth conclusion. The present experimental results indicate that an applied static field may be used to enhance silicon transport in LPD to obtain a more favorable (flatter) growth interface for less inclusions in the grown crystals.