Question

For forward biased diode
1. Transition capacitance is larger than diffusion capacitance
2. Diffusion capacitance is larger than transition capacitance
3. Both capacitances are having same value
4. Cannot predict with certainty

Answer 1

Correct Answer - Option 2 : Diffusion capacitance is larger than transition capacitance

• Capacitors store electric charge in the form of an electric field.
• Transition capacitance is what we normally refer to as a junction capacitance or depletion capacitance. This capacitance is there whenever there is a junction or increases in voltage.
• Diffusion capacitance is caused by a minority carries diffusion. When PN diode is forward biased, the conduction mechanism is mainly due to minority carrier diffusion.
• But diffusion capacitance depends on the current. Higher the current, the higher the capacitance.
• In a forward-biased diode, the transition capacitance exists. However, the transition capacitance is very small compared to the diffusion capacitance, hence it is neglected.