White LED

 A white LED is composed of the insulating substrate made of sapphire, long crystal layer of gallium nitride, n-type buffer layer of gallium nitride, p-type contact layer of gallium nitride, p-type limiting layer of aluminium gallium nitride, multiple quantum-trap luminescent layer of indium gallium nitride, n-type contact layer of gallium nitride,transparent conducting layer of indium tin oxide, n-type front Ni/Au electrode, and p-type back Ni/Au electrode.