|Aim||To draw the I-V characteristics curves of a p-n junction in forward bias and reverse bias.|
|Apparatus Required||P-N junction diode|
DC power supply
Rheostat or potentiometer
|Theory||A p-n junction is formed by joining a p-type semiconductor (with excess holes) and an n-type semiconductor (with excess electrons) together. When a forward bias voltage is applied across the p-n junction, the holes from the p-type semiconductor diffuse across the junction and combine with the electrons in the n-type semiconductor, creating a flow of current. When a reverse bias voltage is applied across the p-n junction, the electrons and holes are pushed away from the junction, creating a depletion region with no charge carriers.|
|Procedure||Connect the p-n junction diode to the DC power supply, rheostat or potentiometer, ammeter, and voltmeter using connecting wires.|
Set the rheostat or potentiometer to its minimum value.
Connect the ammeter in series with the p-n junction diode and the voltmeter in parallel.
Gradually increase the forward bias voltage by adjusting the rheostat or potentiometer and record the corresponding values of current and voltage.
Plot the I-V characteristics curve for the p-n junction in forward bias.
Reverse the connections of the p-n junction diode with the DC power supply.
Repeat steps 2-5 for the reverse bias voltage and record the corresponding values of current and voltage.
Plot the I-V characteristics curve for the p-n junction in reverse bias.
|Observation and Result||Observation:|
In forward bias, the current increases rapidly with increasing voltage.
In reverse bias, the current initially remains low but increases rapidly at a certain voltage known as the breakdown voltage.
The I-V characteristics curve for forward bias is non-linear, while the curve for reverse bias is linear.
The I-V characteristics curves for the p-n junction diode in forward and reverse bias have been successfully plotted.
The curves show the relationship between current and voltage for the p-n junction diode in different bias conditions.
The breakdown voltage for the p-n junction diode in reverse bias can be determined from the curve.