Explanation:
A power diode is a semiconductor device that allows current to flow in only one direction. When a diode is turned off, a reverse voltage is generated across it due to the stored charge. This reverse voltage can cause oscillations in the circuit. The softness factor (S-factor) of a diode is a measure of how quickly the diode turns off. A diode with a small S-factor turns off slowly, which can cause large oscillatory over voltages.

Large oscillatory over voltages:
When a diode turns off slowly, the reverse voltage across it can oscillate. This is because the stored charge in the diode causes the voltage to fluctuate. A diode with a small S-factor is more likely to oscillate than one with a large S-factor. These oscillations can cause large over voltages that can damage the diode or other components in the circuit.

Small oscillatory over voltages:
A diode with a large S-factor turns off quickly, which reduces the amount of stored charge in the diode. This reduces the likelihood of oscillations and reduces the over voltage across the diode. A diode with a large S-factor is better for high-frequency applications where oscillations can cause problems.

Large peak reverse current:
A diode with a small S-factor may also have a large peak reverse current. This is because the slow turn-off time allows more current to flow in the reverse direction before the diode fully turns off. This can cause overheating and damage to the diode.

Small peak reverse current:
A diode with a large S-factor has a smaller peak reverse current because it turns off more quickly. This reduces the amount of current that flows in the reverse direction before the diode fully turns off. This reduces the risk of overheating and damage to the diode.

Conclusion:
A power diode with a small S-factor has large oscillatory over voltages and may also have a large peak reverse current. A diode with a large S-factor has small oscillatory over voltages and a small peak reverse current. The choice of diode depends on the application and the requirements of the circuit.