Question

Explain briefly with the help of necessary diagrams, the forward biasing of a p-n junction diode. Also draw characteristic curves.

Answer 1

p-n junction diode under forward bias

p-side is connected to positive terminal and n-side to the negative terminal.

Applied voltage drops across the depletion region.

Direction of applied voltage (V) is opposite to the build in potential (V₀).

As the depletion layer width decreases, the barrier height is reduced.

Effective barrier height under forward bias is (V₀ − V).

• Electron in n-region moves towards the p-n junction and holes in p-region move towards the junction. The width of the depletion layer decreases and hence, it offers less resistance.

• Diffusion of majority carriers takes place across the junction.

This leads to forward current.