Its dominant type used commercially is silicon; transistors and solar cells are created with them.
The planar process was invented to manufacture things out of one of these materials. The most popular method for producing boules of one type of this material is the Czochralski process. If certain consecutive energy minima and maxima do not lie at the same momentum value, phonons must mediate generation and recombination processes in these materials, and they are classified as indirect. Adding impurities to these materials changes them to extrinsic and is done with a process called doping, which adds energy levels to their band gap. Its dominant type used commercially is silicon; transistors and solar cells are created with them. For 10 points, identify these materials that have a conductivity intermediate between that of conductors and insulators.
The planar process was invented to manufacture things out of one of these materials.
semiconductors [or silicon wafers until \"silicon\" is read; prompt on crystals]