Fig 1.12 Characteristics of PN Junction Diode
The generalized voltage-current characteristic for a p-n junction in Figure above shows both the reverse-bias and forward-bias regions.
- At zero voltage: The barrier does not permit any current to flow through it.
- Forward-bias: Current rises rapidly as the voltage is increased and is quitehigh.
- Reverse-bias: The junction offers a very high resistance called reverse resistance.
Some amount (very small) of free holes and electrons still manage to cross the junction and constitute a reverse curren
Other Important terms:
- If the reverse bias is made very high, a large number of electron-hole pairs are created and the reverse current increases to a relatively high value. The maximum reverse potential difference, which a diode can tolerate without breakdown is called reverse break down voltage or zener voltage.
In other words, the minimum reverse voltage at which a pn junction breaks down is called the breakdown voltage.
- Knee Voltage: The voltage at which the pn junction begins to conduct currentand shows rapid rise in the current.
- Maximum forward voltage: The highest forward current that the pn junctioncan conduct without any damage to the junction
- Peak Inverse Voltage(PIV): It is the maximum reverse voltage that can beapplied to a pn junction without any damage to the junction
Beyond PIV, the junction diode is destroyed due to excessive heat.
- Maximum power rating: It is the maximum power that can be dissipatedthrough the junction without damaging it.
- It is equal to the product of junction current and voltage across the junction.
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