COMEDK20269 May 2026Morning ShiftPhysicsSemiconductorsActual
In a PN junction diode, the forward bias is increased gradually from 0 Volt to 1 Volt. Which of the following statements is correct?
Options
- AThe depletion width increases, and barrier potential increases
- BThe depletion width decreases, but the electric field inside the junction increases
- CThe depletion width remains unchanged, but current increases
- DThe depletion width decreases and barrier potential decreases
Correct answer
D. The depletion width decreases and barrier potential decreases
Step-by-step solution
In a PN junction diode, the built-in potential (barrier potential) acts from the n-side to the p-side. When the diode is forward biased, the applied voltage opposes the built-in potential. The effective barrier potential becomes V₀ - V_f , where V₀ is the built-in potential and V_f is the applied forward bias voltage. Thus, the barrier potential decreases. The width of the depletion region is directly proportional to the square root of the effective barrier potential, given by W V₀ - V_f . As the effective barrier