A sheet wafer growth system includes a crucible for containing molten material and an afterheater positioned above the crucible. The afterheater has an inner surface disposed toward the crucible. The system further includes one or more shields adjacent to the inner surface of the afterheater. The afterheater and the shield(s) are configured to allow a sheet wafer to pass adjacent to the shield(s). Each shield has two or more substantially different thermally conductive regions such that the two or more regions are configured to control the temperature profile of the growing sheet wafer.