pn Junction

pn Junction

1. forward bias

   • the pn junction p-type connected to positive terminal and n-type connected to negative terminal, the potential barrier is reduced.

2. reverse bias

   • the pn junction p-type connected to negative terminal and n-type connected to positive terminal, potential barrier at the junction is increased.
   • reverse saturation current
     • practically no current flows through the circuit. However, in practice, a very small current (of the order of μA) flows in the circuit with reverse bias, and is due to the minority carriers.

3. IMPORTANTS TERMS

   • knee voltaje
     • It is the forward voltage at which the current through the junction starts to increase rapidly.
     • breakdown voltage
       • It is the minimum reverse voltage at which pn junction breaks down with sudden rise in reverse current.
       • avalanche effect
         • The newly liberated electrons in turn free other valence electrons. In this way, we get an avalanche of free electrons. Therefore, the pn junction conducts a very large reverse current.

4. Limitations in the Operating Conditions of pn Junction

   • Maximum forward current.
     • Peak inverse voltage (PIV).
       • Maximum power rating.
         • It is the maximum power that can be dissipated at the junction without damaging it.
       • It is the maximum reverse voltage that can be applied to the pn junction without damage to the junction.
     • It is the highest instantaneous forward current that a pn junction can conduct without damage to the junction.