N typeP type (donor impurities)(acceptor impurities) -antimony-aluminum -arsenic-boron -bismuth-gallium -phosporus-indium

Charge carriers are those that inhibits current conduction in a semiconductor which are either electrons (-) or holes (+).

The dominating charge carriers, whether holes or electrons, are the majority carriers. The less abundant ones are the minority carriers.

In a N type semiconductor, most of the current flows as “electrons” passing from atom to atom. This defines an electron flow.

In a P type semiconductor, most of the current flows as an “electron absence”. The absences, called “holes”, move in a direction opposite to that of the electrons. This defines the hole flow.

A resistor must be included in a circuit to prevent destruction of the diode by the excessive current.

This is essential for conduction to occur, wherein, it varies from about 0.3V to 1V. Its application can be useful in amplitude limiters, waveform clippers and treshold detectors.

 Forward bias  Reverse bias

Some P-N junctions can alternate between conduction (in forward bias) and nonconduction (in reverse bias) millions or billions of times per second. Other junctions are slower.

The capacitance is the main limitting factor at the P-N junction during conditions of reverse bias.

 Operating voltage  Type of semiconductor material  Cross-sectional area of the P-N junction

Junction capacitance can be varied by changing the reverse- bias voltage, because the voltage affects the width of the depletion region.

“If the reverse bias goes past teh critical value of depletion, the voltage overcomes the ability of the junction to prevent the flow of current, and the junction conducts as if it were forward biased.”

Some components are designed to take advantage of the avalanche effect. In other cases, avalanche effect limits the performance of a circuit.