A potential barrier of 250 meV exists across a p - n junction. A hole possessing a kinetic energy of 300 meV approaches the junction from the n -side. Determine the kinetic energy of the hole after it crosses the junction.

Step-by-step solution

In a p - n junction, the n -side is at a higher electric potential than the p -side due to the built-in potential barrier. The electric field in the depletion region is directed from the n -side to the p -side. A hole acts as a positive charge. When it approaches the junction from the n -side and moves towards the p -side, it moves in the direction of the electric field. Thus, it moves from a higher potential to a lower potential. The loss in potential energy of the hole is equal to the potential barrier energy, wh