1. Because it is the most common rectifier, a p-n junction has many circuit applications.
2. Many devices are special forms of p-n junction. Examples are LED, laser, solar cell, and photodiode. A p-n junction also serves as a building block for many other devices such as the bipolar transistor, MOSFET, junction FET, etc.
3. Due to the non-linear, exponential nature of the current, the p-n junction can be used as a varistor.
4. The variable depletion capacitance at reverse bias can be utilized as a varactor.
5. A p-n junction is a very common protection device for electro-static discharge (ESD). It discharges a voltage surge when it exceeds a certain value comparable to the built-in potential.
6. A p-n junction is a robust device and is a good choice for a diode required in power electronics.
7. The p-n junction can be used to isolate devices or regions of semiconductors. An example can be found in the tub isolation for CMOS circuits.
8. The well-behaved forward characteristics of a p-n diode enable it to be used as a temperature sensor. In operation, a constant current is applied and the voltage is monitored. This forward voltage drop is a fairly linear function of temperature. GaAs diodes can be good sensors in a wide temperature range from a few degree К to » 400 K, and Si diode from » 20 K.
