Light-emitting diode into a lower energy level and releases energy in the form of a photon. The wavelength of the light emitted, and thus its color, depends on the band gap energy of the materials forming the "p-n junction". In silicon or germanium diodes, the electrons and holes usually recombine by a "non-radiative transition", which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light. LED development began with infrared and red devices made with gallium arsenide. Advances in materials science
LED tattoo LED tattoo A light-emitting diode tattoo is a type of body modification similar to a tattoo, but specifically involves implantation of technologically based materials versus traditional ink injection into the layers of the skin. LED tattoos are accomplished by a combination of silicon-silk technology and a miniature lighting device known as a light-emitting diode. While there is potential for many applications in the medical, commercial and personal domains, the technology is still in the development stage. Once the ability is attained to condense the parts of a LED to a small enough level, it will be possible for the tattoos