Light-emitting diodes (LEDs) and laser diodes with wavelengths below the red ( Gallium nitride and other III-V nitride-based semiconductors have a direct band gap that is suitable for blue light-emitting devices. The band gap energy of aluminum gallium indium nitride (AlInGaN) varies between 6.2 and 2.0 eV, depending on its composition at room temperature. Therefore, using these semiconductors, we can fabricate emitters with outputs between the red and UV.