LED refers to Light-Emitting Diodes. Light Emitting Diodes are semiconductor
devices that emit light by only allowing electric current to pass in one direction.
LEDs consist of two elements: N-type and P-type semiconductors.
The two materials are placed in direct contact as seen in Figure 1:
The P-type silicon contains excessive positive charges representing an absence of
electrons. The N-type silicon contains a number of negative charges (electrons).
When a current is passed through the semiconductor device electrons move from the
N-type silicon to the P-type silicon, while the excessive charges move towards the N-type
silicon meeting at what is known as a PN Junction (see Figure 2).
