Shuji Nakamura, Nichia Chemical Industries
Light-emitting diodes (LEDs) and laser diodes with wavelengths below the red (< 635 nm) hold significant promise for holographic memories, compact discs (CDs) and printers among other devices. As such, much development has gone into the search for blue-emitting diode lasers.
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.