Abstract: A process for producing a doped silicon single crystal, comprising after-doping the melt during the pulling process with a quantity of volatile dopant ?N(t), calculated according to the equation ?N(t)=N0?N(t)=N0·(1?e??a·t) or according to the approximation equation ?N(t)=N0·?a·t where ?a is an evaporation coefficient which describes process-specific evaporation behavior of the foreign substance and which is obtained after a resistance profile R(t) of a further single crystal has been measured and calculated according to the equation R(t)=R0·e?a·t, where R0 is a starting resistivity and the further single crystal is pulled under the same process conditions without being after-doped with the foreign substance.

Abstract: A process for producing a silicon single crystal which is doped with highly volatile foreign substance by pulling the single crystal from a melt which is held under predetermined process conditions in a crucible. A quantity of the foreign substance N0 is added in order to achieve a desired resistance of the melt, and the melt, after a time t, is after-doped at least once with a quantity &Dgr;N(t) of the foreign substance, in order to compensate for losses caused by the foreign substance evaporating out of the melt.

Abstract: A method for doping a melt with a dopant has the melt being provided in a crucible. The dopant is introduced into a vessel and the vessel is immersed in the melt, the dopant being transferred into the melt through an opening which forms in the vessel. There is also an apparatus which comprises a vessel containing the dopant and a device which is connected to the vessel, for lowering the vessel into a melt and for lifting the vessel out of the melt, the vessel being provided with an opening which is blocked by a closure piece which is of the same type of material as the melt and melts when it is brought into contact with the melt.

Abstract: A method for doping a melt with a dopant has the melt being provided in a crucible. The dopant is introduced into a vessel and the vessel is immersed in the melt, the dopant being transferred into the melt through an opening which forms in the vessel. There is also an apparatus which comprises a vessel containing the dopant and a device which is connected to the vessel, for lowering the vessel into a melt and for lifting the vessel out of the melt, the vessel being provided with an opening which is blocked by a closure piece which is of the same type of material as the melt and melts when it is brought into contact with the melt.

Abstract: A heating element for heating crucibles, including a cylindrical hollow body which is divided by slits into meandrous segments. The corners between adjacent lateral surfaces of the meanders are rounded. Sectional transition areas are located in the vicinity of the upper and lower edges of the meandrous segments. Each sectional area has an outer rounded edge with a radius of curvature equal to the individual length of each meandrous section.

Abstract: Apparatus for preparing a single crystal made of silicon is according to Czochralski method, which includes a tubular to the conical body which shields the growing single crystal and divides the receiver chamber above the melt into an inner portion and an outer portion, the body having at least one orifice through which inert gas which is conducted into the inner portion of the receiver chamber is able to pass directly into the outer portion of the receiver chamber. The method for preparing a single crystal made of silicon is in accordance with the Czochralski method, wherein a portion of an inert gas stream is conducted through at least one orifice in the tubular to conical body from the inner portion into the outer portion of the receiver chamber.