| S. M. Condren, G. C. Lisensky, A. B. Ellis, K. J. Nordell, T. F. Kuech, and S. A. Stockman, "LEDs: New Lamps for Old A Paradigm for Ongoing Curriculum Modernization", J. Chem. Ed., Vol. 78, 1033(2001). |
Families of semiconductors can be incorporated into devices that emit light over much of the visible spectrum upon electrical excitation. These light emitting diodes (LEDs) and diode lasers are revolutionizing many communication and display technologies. The wavelengths of light emitted can be controlled using design principles based on the periodic table, including isovalent element combinations and solid solutions. A recent technological breakthrough is the blue LED, which permits additive color mixing when combined with green and red LEDs.
The term "diode" refers to the fact that unlike a normal light bulb, which will light up when electricity flows through it in either direction (by, e.g., hooking it up to a battery in either direction), the LED will only light up when electricity flows in one direction because of the electric fields that are present in the interior of the device.
A simple circuit can be constructed with the LED, a 1K ohm resistor and a 9-volt battery. The resistor limits the amount of electrical current flowing through the diode so that it doesn't overheat, which can destroy it.
Forward [Band Theory]