What does the term 'potential barrier' describe in semiconductors?

• A. Space between two different types of joined semiconductor material
• B. A metal-insulator boundary
• C. An energy gap in a conductor
• D. A magnetic boundary

Answer: (A)

A potential barrier in semiconductors is the built‑in electrical barrier that forms at the interface where two differently doped semiconductor materials meet, such as a p-type and an n-type region. When these regions come into contact, carriers diffuse across the junction, leaving behind charged ions in a depletion region. This creates an internal electric field and a corresponding potential difference across the junction. That potential difference acts as a barrier to further carrier movement, opposing diffusion. The barrier can be lowered by forward bias, allowing current to flow, or increased by reverse bias, reducing the current. This barrier is specifically the space between the two joined semiconductor materials where the depletion region and electric field exist.