Question

Draw the circuit diagram of a p-n junction diode in
(i) forward biasing and
(ii) reverse biasing.
Also, draw its I-V characteristics in the two cases.

Hint:

In forward bias, current flows easily after the threshold voltage. In reverse bias, only a small leakage current exists until breakdown.

Answer 1

Understanding p-n Junction Diode Biasing 

- A p-n junction diode allows current flow in one direction (forward bias) and blocks current in the opposite direction (reverse bias). 
(i) Forward Biasing: 
- The p-side (anode) is connected to the positive terminal of the battery, and the n-side (cathode) is connected to the negative terminal. 
- This reduces the depletion region width, allowing current to flow. 
Circuit Diagram for Forward Biasing: 
I-V Characteristics in Forward Bias: 
- The current increases exponentially after the threshold voltage (0.7V for silicon, 0.3V for germanium). 
(ii) Reverse Biasing: 
- The p-side is connected to the negative terminal, and the n-side is connected to the positive terminal. 
- This increases the depletion region width, preventing current flow (except for a small leakage current). 
Circuit Diagram for Reverse Biasing: 
I-V Characteristics in Reverse Bias: 
- A small leakage current flows until the breakdown voltage is reached.