Explain the construction of a MOSFET. Draw the symbols and diagrams of both P-channel and N-channel MOSFET.

As JFET and MOSFET also have source, drain and gate. Its gate is insulated by its conducting channel through an ultra-thin metal oxide insulating film (generally of silicon dioxide SiO₂), due to this insulating property; MOSFET is also termed as insulated gate field effect transistor that is IGFET or IGT. Now also, gate voltage controls the drain current but the major difference among JFET and MOSFET is that, we can apply both positive and negative voltages to the gate since this is insulated from the channel, in later case. Furthermore the gate, SiO₂ insulator and channel form a parallel plate capacitor. Not like JFET, a MOSFET has only one p- region or n-region termed as substrate as demonstrated in the figure (a) and figure (b). Normally this is shorted to the source internally. Symbols of both N- channel and P- channel MOSFET are demonstrated below.

                  Symbols of P and N channel MOSFET