Now, we wish to apply a voltage to the LED and see what happens to
Use the slider control (upper left) to vary the voltage (input energy) applied the LED. The energy diagrams show how the energy level responds to the voltage.
What is the effect on the energy bands as the applied voltage changes from 0.0 Volts to +1.0 Volts?
To apply a negative voltage we need to flip the LED and place it in the circuit with the wires reversed (long lead on the right). Use the flip button to reverse the LED. What is the effect on the energy bands as the applied voltage changes from +1.0 Volts to -1.0 Volts by flipping the LED?
For which of the two applied voltages (-1.0 Volts or +1.0 Volts) would it be more likely for the electrons to move from the conduction band of the right block to the conduction band of the left block? Explain.
Reverse the LED again by flipping it so that the long lead is on the left. Move the slider to the minimum voltage necessary for the LED to begin emitting light. Recall we defined this voltage as the threshold voltage.
What happens to the energy bands of the two semiconductor blocks when the threshold voltage is applied to the LED?
Using the table below record the threshold voltage displayed on the voltmeter and indicate the LED that you were using. Record the range of energies (in eV) of the output spectrum of your LED and the energy gap. Repeat for 5 LEDs.