Patent ID: 7811383

Claim:
A device for production of a monocrystalline or a multicrystalline material blank using a vertical-gradient-freeze method, said device comprising: a fixed crucible with a bottom end and a top end, if viewed in a longitudinal direction, said fixed crucible having a crucible wall and a polygonal cross section, and a flat heating device for melting silicon in the crucible, which is arranged around the crucible to suppress a heat flow perpendicular to the longitudinally direction and which is configured to form a temperature gradient in the crucible in the longitudinal direction; wherein said flat heating device comprises a plurality of flat heating elements, which are embodied as rectangular webs, which are arranged on side faces of the crucible in a meandering course in the longitudinal direction or vertically thereto, and wherein the course of the webs inverts direction in inversion zones at corner areas of the polygonal cross section of the crucible; and wherein said flat heating elements are structured so that the heat outputs of the flat heating elements are increased at the inversion zones of the meandering course at the corner areas of the polygonal cross section of the crucible in comparison to heat outputs at other areas not at the corner areas of the polygonal cross section; or wherein distances between the flat heating elements and the crucible wall at the corner areas are smaller than distances between the flat heating elements and the crucible wall at other areas not at the corner areas of the polygonal cross section.