Patent ID: 7195671

Claim:
An apparatus for growing crystals, comprising: a sealed chamber having a crucible assembly and a seed holder disposed therein, said seed holder being selectively positionable within said chamber from a first position relative to said crucible assembly to at least one subsequent position within said crucible assembly, said crucible assembly adapted to contain a melt therein; a heater sufficiently configured and dimensioned to heat said melt disposed within said crucible assembly; an insulator for insulating said heater and said crucible assembly; an actuator for rotating at least one of said crucible assembly and said seed holder relative to the other; a support ring for suspending said crucible assembly within said sealed chamber; and a thermal shield disposed atop said support ring for regulating the heat loss from the crucible assembly to an upper portion of said chamber, said thermal shield having at least one wall made from a ceramic material having a low coefficient of thermal expansion and providing insulation primarily from above said crucible assembly.