The following are the graphs of potential barrier versus width of the depletion region for a p-n junction diode. Which of the following is correct? I II III IV A - unbiased diode A - Forward biased diode A - unbiased diode A - unbiased diode B - Reverse biased B - Reverse biased B - Forward biased B - unused diode C - Forward biased C - unbiased C - Reverse biased C - Forward biased

Step-by-step solution

Forward biased diode: external voltage opposes built-in potential reduced barrier height and narrower depletion region Graph C (lowest, narrowest). Reverse biased diode: external voltage adds to built-in potential increased barrier and wider depletion region Graph B (highest, widest). Unbiased diode: natural built-in potential, intermediate width Graph A. Matching: A - unbiased, B - reverse biased, C - forward biased Column I is correct.