LED basic concepts
Actually, light-emitting diode shorthand is LED. Different light-emitting diodes materials will launch different light color .
For example，The light-emitting diodes is normally made of the gallium(Ga), arsenic(As), phosphorus(P) compounds,then GaAsP-light-emitting diode Show up the red light,then GaP-light-emitting diode Show up the green light,then SiC-light-emitting diode Show up the yellow light,Which of free electron recombine with the electron hole, it can radiate visible light, so according to this characteristic to make LED.
Led crystals form a covalent bond, the outermost electrons of each atom is eight, constitute a stable structure.
Covalent bonds have a strong binding force, so that can be arranged atoms regularly, form crystals,the two electrons(in formation of the covalent) are bound tightly , known as valence electron or bound electron.After valence electrons to obtain a certain energy (temperature or by light), to break the shackles of the atomic nucleus,become free electrons (with negative charge),while leaving a space in the covalent bond ,called electron holes (positively charged).