Process for producing a single crystal from silicon

1:

• A process for producing a single crystal of silicon, the process comprising:
• installing a feed rod of silicon in a float-zone apparatus, the feed rod having a diameter of not less than 230 mm and not more than 270 mm;
• installing a first hollow cylinder having a bottom edge and an internal diameter, which is larger, by not less than 30 mm and not more than 50 mm, than the diameter of the feed rod;
• installing a second hollow cylinder having a top edge and an internal diameter, which is larger, by not less than 20 mm and not more than 60 mm, than a target diameter of the single crystal;
• pulling a cylindrical part of the single crystal, which has the target diameter of not less than 290 mm and not more than 310 mm, wherein
• the feed rod at a melting front forms an outer melting edge and a monocrystalline ingot on a growth side forms a crystallizing edge,
• a pulling speed is not less than 1.3 mm/min and not more than 1.5 mm/min,
• a vertical distance of the bottom edge of the first hollow cylinder from the outer melting edge is smaller than 2 mm, and
• the top edge of the second cylinder protrudes not less than 1 mm and not more than 10 mm over the crystallizing edge;
• and
• removing a length of the single crystal to form an ingot piece having a length of not less than 15 cm and not more than 50 cm.