Positive (P)-type semiconductors are acceptors of electrons, and are commonly paired with negative (N)-type semiconductors as electronic components or integrated circuits (ICs). P-type semiconductors were previously intrinsic semiconductors, such as silicon, that have been combined with small quantities of dopant atoms with three valence electrons. A valence electron is an electron in the outermost electron orbit. For every million atoms of silicon, 0.1 atom of a three-valence atom, such as boron, is added. The process of adding a dopant, such as boron, is known as doping.
Silicon occurs in nature as silicon dioxide or silica sand. Chemical experts separate the oxygen from the silicon dioxide and process pure silicon by heating and doping to produce P-type semiconductors. P-type material production requires super clean and super high temperatures in an inert environment, such as a vacuum. Some companies specialize in the first-phase semiconductor production, which is the production of semiconductor wafers for other semiconductor manufacturers.
N-type semiconductors are just as important as P-type semiconductors because together, they are the building blocks of electronic circuits. Diodes use one of each type of semiconductor in making a positive-negative (P-N) junction. Transistors use one and then two of the other type, such as the negative-positive-negative (NPN) transistor.
In the simplest applications, a P-type semiconductor is joined to an N-type semiconductor to form a diode. Connection leads are bonded to the free ends of the semiconductor material opposite the P-N junction, and the lead connected to the P-type is referred to as the anode, while the other is called the cathode. Using 6 volts direct current (VDC) power supply, current meter, and a limiting resistance in series with the new diode, the current flows when the cathode is negative with respect to the anode, a condition known as forward bias. Reverse bias condition occurs when the cathode is positive while the anode is negative. This mechanism is the reason why the diode is referred to as a one-way valve.
There is an interesting common effect in doping a semiconductor and allowing even super small amounts of contaminants in the production process. A small amount of dopant or random contaminants is able to significantly alter the characteristic of the parent intrinsic semiconductor. This justifies the mission-critical investment in a clean environment, owing for the need for body wear that shields the entire human body of semiconductor production personnel from the semiconductor materials during production.
