Give the forward biased and reverse biased characteristics of a p-n junction diode.

Sure, here is the step-by-step explanation:

Forward Biased Characteristics of a p-n Junction Diode:

1. Definition: When the p-side (anode) of the diode is connected to the positive terminal of the power supply and the n-side (cathode) is connected to the negative terminal, the diode is said to be forward biased.

2. Barrier Potential: In forward bias, the external voltage reduces the potential barrier of the p-n junction. For silicon diodes, this barrier potential is approximately 0.7V, and for germanium diodes, it is about 0.3V.

3. Current Flow: Once the applied voltage exceeds the barrier potential, charge carriers (electrons and holes) gain enough energy to cross the junction, resulting in a significant increase in current. This current increases exponentially with the increase in applied voltage.

4. I-V Characteristics: The current-voltage (I-V) characteristic curve in forward bias shows a small current at low voltages (below the threshold voltage), followed by a sharp increase in current as the voltage exceeds the threshold.

Reverse Biased Characteristics of a p-n Junction Diode:

1. Definition: When the p-side (anode) of the diode is connected to the negative terminal of the power supply and the n-side (cathode) is connected to the positive terminal, the diode is said to be reverse biased.

2. Barrier Potential: In reverse bias, the external voltage increases the potential barrier of the p-n junction, making it more difficult for charge carriers to cross the junction.

3. Current Flow: In reverse bias, a very small current, known as reverse saturation current (leakage current), flows through the diode. This current is due to the minority charge carriers and is typically in the microampere range.

4. Breakdown Voltage: If the reverse voltage is increased beyond a certain point, known as the breakdown voltage, the diode will undergo breakdown, leading to a large increase in current. This can occur through mechanisms such as avalanche breakdown or Zener breakdown, depending on the diode's construction and doping levels.

5. I-V Characteristics: The I-V characteristic curve in reverse bias shows a very small current up to the breakdown voltage, beyond which the current increases sharply.

These characteristics are fundamental to understanding the behavior of p-n junction diodes in various electronic circuits.