All FETs can be called UNIPOLAR devices, because charging carriers carrying the current through the device are all of the same type, that is, either holes or electrons, but not both. This distinguishes FETs from bipolar devices in which both holes and electrons are responsible for the current flow in any device.
Bipolar Transistor (BJT)
The bipolar transistors are named so because the main conduction duct uses two polarities of the load carriers: the electro and the holes, to carry an electric current.
The operation of the BJT can be dibayang because the two diodes are positive or negative, so that there are 3 terminals, that is base (B), (C), collector, and Emmitter (E).
Changes in the electrical current in small quantities to the base terminal can significantly change a large amount of electrical current to collector terminals. This is the underlying principle of using the transistor as an amplifier’s electronics. The ratio of the current flow collector current to the base is usually β or hFE symbolized. β usually ranges from about 100 to transistor BJT transistors.
Unipolar Transistor (FET)
Unipolar transistors (FETSs) that use only one type of charge carriers (electrons or holes, depending on the type of FET). In FETS, an electric current flows into a main channel with a narrowed area conduction on both sides (compared to the bipolar white transistor, the leading region cut direction affects the lidtrik currents). And the thickness of the edge area can be changed with the change of the given voltage to change the thickness of the conduit channel.