Experiment 03 · Circuit Diagram
Band Gap of Semiconductor
Two separate circuits share this bench. The measuring loop reads the current leaking backwards through the diode. The heater loop warms the oven off the mains. They must never touch one another.
Procedure
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1.
Connect the circuit as per the given circuit diagram. To wire two terminals together, click on one terminal and drag the cursor to the other.
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2.
Once all the connections are complete, click on the thermometer to place it inside the oven.
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3.
Set the reverse bias voltage to 5 V.
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4.
Switch on the oven and let the temperature rise to about 80°C.
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5.
Switch off the oven and allow the diode to cool down gradually.
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6.
As it cools, record the temperature T and the corresponding reverse saturation current, Is, at regular intervals.
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7.
Use the first formula below to work out the analytical, theoretical value of the band gap energy, Eg.
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8.
Plot ln(Is) against 1/T, find the slope of the line, and use the second formula below to get the graphical, experimental value of Eg.