FET
Source, drain, and gate are the three terminals that make up a field effect transistor. The majority charge carriers enter the FET through the source terminal, and the majority charge carriers exit the FET through the drain terminal. Diffusion of an N-type semiconductor and a P-type semiconductor results in the formation of the gate. As a result, a region of the PN junction that controls the carrier's flow from source to drain is heavily doped. The drain current is governed by the voltage applied between the gate and the source (Id). This indicates that the output current is controlled by the voltage difference between the gate and source (Vgs). FET is therefore known as the voltage controlled device. Due to the fact that this device only uses either electrons (n-channel) or holes (p-channel) as charge carriers during operation, not both, it is also known as a unipolar device.