To investigate the variation of current ( I ) with pd ( V ) for a semiconductor diode
When a voltage source is connected to a semiconductor diode (silicon) a current flows through the diode. In this experiment we investigate
how the current flowing through the diode varies with different voltages applied across it when it is forward biased and when reverse biased.
- Note that the diode is forward biased and that current is 0 when voltage is 0. Record voltage and current values in a table.
- Click on the slider to increase the voltage from the potentiometer.
- Record the voltage and current readings from the voltmeter and ammeter.
- Repeat steps 2 and 3 until you have exceeded the junction voltage and the current increases rapidly.
- Set voltage to zero and click on "Reverse Biased". Note the changes that occur. Increase voltage and note current.
Draw a graph of current (y-axis) against voltage to determine the relationship between them. When the diode is
forward biased the current is measured in milliamps, when reverse biased the current is measured in microamps.
Make sure you understand the significance of the graph in terms of forward and reverse bias and junction voltage.
All Physics Experiments
- Use a microammeter when the diode is reverse biased as the current flowing is extremely small.
- Change the positions of the microammeter and voltmeter when reverse biased so that the current flowing through the
diode is the only one registered in the microammeter (not current through the voltmeter).