saad
Advanced Member level 4
built in potential
The built in potential ( or barrier potential ) for pn junctions is given by following relation,
Vbi = Vt ln(Na*Nd/ni²) which is normally of the order of 0.6V to 0.8 V.
It can be seen that Vbi is purely function of Temperature and Doping and independent of the external bias
Incase of forward biased Pn junction, the barrier is reduced to
barrier = Vbi-Vf --------- Eq (1)
where Vf is the applied forward bias potential.
What happens if Vf > Vbi?
From Equation (1) => Vbi-Vf <0
How can we justify a negative barrier across the pn junction?
The built in potential ( or barrier potential ) for pn junctions is given by following relation,
Vbi = Vt ln(Na*Nd/ni²) which is normally of the order of 0.6V to 0.8 V.
It can be seen that Vbi is purely function of Temperature and Doping and independent of the external bias
Incase of forward biased Pn junction, the barrier is reduced to
barrier = Vbi-Vf --------- Eq (1)
where Vf is the applied forward bias potential.
What happens if Vf > Vbi?
From Equation (1) => Vbi-Vf <0
How can we justify a negative barrier across the pn junction?