In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction
(a) from the p-side and
(b) from the n-side
Potential barrier, d = 250 meV
Initially the kinetic energy of the hole = 300 meV
(a) When the hole approaches the junction from p-side, junction will act like forward biasing.
Therefore, the kinetic energy of the hole will decrease.
Final kinetic energy of the hole = (300-250) meV
= 50 meV
(b) When the hole approaches the junction from n-side, junction will act like reverse biasing.
Therefore, the kinetic energy of the hole in this case will increase.
Final kinetic energy of the hole = (300+250) meV
= 550 meV