away from the gate-insulator/semiconductor interface, leaving exposed a carrier-free region of immobile, negatively charged acceptor ions (see doping). If V_G is high enough, a high concentration of negative charge carriers forms in an inversion layer located in a thin layer next to the interface between the semiconductor and the insulator.

Conventionally, the gate voltage at which the volume density of electrons in the inversion layer is the same as the volume density of holes