The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors and is used  mainly in the production of  large cylindrical ingots or boules of single crystal silicon. This high grade silicon is used in the electronics industry as well as manufacture of crystalline silicon solar panels. High-purity, semiconductor-grade silicon (only a few parts per million of impurities) is melted in a crucible (usually made of quartz) at 1,425° C. Dopant impurity atoms such as boron or phosphorus can be added to the molten silicon in precise amounts to dope the silicon, thus changing it into p-type or n-type silicon, with different electronic properties. A precisely oriented rod-mounted seed crystal is dipped into the molten silicon. The seed crystal’s rod is slowly pulled upwards and rotated simultaneously. By precisely controlling the temperature gradients, rate of pulling, and speed of rotation, it is possible to extract a large, single-crystal, cylindrical ingot from the melt.