Czochralski Silicon

Single crystalline substrates are typically differentiated by the process by which they are made. Czochralski (Cz)[1] wafers are the most commonly used type of silicon wafer, and are used by both the solar and integrated circuit industry. The process of making a large single crystalline silicon ingot by the Czochralski process is shown below. The use of quartz crucibles in the manufacture of Cz substrates causes the incorporation of ppm  (1018 cm-3) oxygen into the silicon ingot. The oxygen itself is relatively benign but creates complexes with boron doping that degrades the carrier lifetime.[2][3][4] N-type ingots fabricated with phosphorous dopants have similar oxygen concentrations but do not show the degradation effect nor do wafers with lower resistivity or gallium dopants. [5]

Top of Czochralski ingot. The bottom cylindrical section has been cut off to make wafers. Such "tops and tails" left over from growing the semiconductor industry are a large source of silicon supply for the photovoltaics industry.