Semiconductors and Diodes

Semiconductors are made from material somewhere between the ranges of conductors and nonconductors. Semiconductors, basically, are designed to do one of three things: (1) stop the flow of electrons, (2) start the flow of electrons, or (3) control the amount of electron flow. A semiconductor diode is a two-element solid state electronic device. It contains what is termed a "P" type material connected to a piece of "N" material. The union of the "P" and "N" materials forms a PN junction with two connections. The "anode" is connected to the P material; the "cathode" is connected to the N material. A diode is, in effect, a one-way valve. It will conduct current in one direction and remain non conductive in the reverse direction. When current flows through the diode, it is said to be "forward biased." When current flow is blocked by the diode, it is "reverse biased." When a diode is reverse biased, there is an extremely small current flow; actually, the current flow is said to be "negligible." When the P and N are fused together to form a diode, it can be placed in a circuit. The P material is connected to the positive side of the battery and the N material is connected to the negative side of the battery. Connected in this manner, current will flow. If connected in the reverse manner, current will not flow.