Question

Which of the following statement(s) is/are true regarding potential barrier of p-n junction?

• A. The electric field formed in the depletion region acts as a barrier
• B. External energy must be applied to get the electrons to move across the barrier of the electric field
• C. The potential difference acts as a barrier specifically for the minority carriers of the materials.
• D. All of the above

Answer 1

Answer: (A), (B)

The correct options are
A The electric field formed in the depletion region acts as a barrier
B External energy must be applied to get the electrons to move across the barrier of the electric field

When a p-type crystal is placed in contact with a n-type crystal, a junction diode is formed. At the junction of both crystals, a layer is formed, which don't have any charge carrier (but it has the charge), this is called depletion layer. The p-side of the layer becomes negative and n-side becomes positive, therefore this layer acts as a fictitious battery across the junction.

This layer prevents the further diffusion of charge carriers across the junction, therefore acts as a barrier for charge carriers. Now, if we want to get an electron (majority charge carrier in n-type crystal) to cross the junction, we have to apply an external electric field, which must be greater than the internal field (potential barrier) i.e. external energy must be applied to cross the electrons through the junction.