Part 1: How a Diode Works

When there is no voltage applied to the diode, some of the free electrons in the n-type layer migrate to fill the holes in the the p-type layer. (This occurs without any external voltage applied. Press the start button restart the animation.) The movement of the electrons creates a voltage difference between the two layers known as the barrier voltage.

If a negative voltage is connected to the anode, it forces more electrons into the p-type layer, raising the barrier voltage and cutting off the flow of current. (Press the blue button on the animation for a demonstration.)

If a positive voltage of greater than 0.6 volts is applied to the anode, the barrier voltage is overcome and electrons will flow through the diode. (Press the red button on the animation.)