Semiconductor (often a combination of gallium, arsenic and phosphorous or gallium and nitrogen)
containing an
n region (where electrons are more numerous than positive charges) separated from a
p region (where positive charges are more numerous than negative charges). Upon application
of a voltage, charges move and emission of
ultraviolet,
visible or
infrared radiation is produced each time a
charge recombination takes place. Although a
LED emits incoherent monochromatic light, normally a very narrow
frequency range is obtained.