Diode breakdown

If reverse voltage reaches a critical level, the diode current will start to increase abruptly. Such a phenomenon is called the breakdown of a diode. The value of the voltage breaking down a diode depends on the diode type.

There are two kinds of the barrier layer breakdown: electrical and thermal. When the electrical breakdown happens, the number of charge carriers in a p-n junction increases due to action of a strong electric field.

The thermal breakdown happens under the action of thermal ionization. The electrical breakdown is divided into avalanche and tunneling ones.

Under high reverse voltage, the number of charge carriers in a p-n junction increases abruptly and reverse current increases too. The avalanche breakdown comes.

The tunneling breakdown is determined by electrons transfer from a valance band to a conduction band without changing electron energy (tunnel effect). The electrical breakdown does not damage the p-n junction.

The thermal breakdown happens when the p-n junction is overheated by a reverse current. It causes non-recoverable changes in the structure and damages a diode.