What is a semiconductor LED (light emitting diode)?
A light emitting diode (LED) is a semiconductor diode that emits light of one or more wavelengths (colors). A diode is a device through which electrical current can pass in only one direction. The electrical current injects positive and negative charge carriers which recombine to create light. The diode is attached to an electrical circuit and encased in a plastic, epoxy, resin or ceramic housing. The housing usually consists of some sort of covering over the device as well as some means of attaching the LED to a source of electrical current. The housing may incorporate one or many LEDs. An LED is typically <1 mm2 in size, or approximately the size of a grain of sand. However, when encased in the housing, the finished product may be several millimeters or more across.
