Question

Explain the formation of the depletion layer at the p-n junction diode. Draw the characteristic curve of a reverse-biased junction diode showing Avalanche breakdown.

Hint:

Avalanche breakdown in a reverse-biased diode occurs when the reverse voltage exceeds the breakdown voltage, causing a large increase in current.

Answer 1

Step 1: Formation of Depletion Layer.
At the p-n junction, when a p-type semiconductor is joined with an n-type semiconductor, free electrons from the n-region diffuse into the p-region and recombine with holes, creating a region depleted of charge carriers called the depletion layer.
Step 2: Reverse Bias and Avalanche Breakdown.
When the diode is reverse biased, the depletion layer widens. If the reverse voltage is increased to a critical value (known as the breakdown voltag, avalanche breakdown occurs, causing a large current to flow through the diode.
(Here, you would draw the characteristic curve showing reverse bias and the avalanche breakdown.)
Final Answer:
The depletion layer forms due to the recombination of free electrons and holes at the p-n junction, and avalanche breakdown occurs when the reverse bias exceeds a certain threshold.