AlGaN based deep ultraviolet light emitting diodes with high internal quantum efficiency grown by molecular beam epitaxy

We report the development of AlGaN based deep ultraviolet light emitting diodes (UV-LEDs) by molecular beam epitaxy. By growing the AlGaN well layer under Ga-rich conditions to produce strong potential fluctuations, internal quantum efficiency of a quantum well structure emitting at 300 nm was found to be 32%. By combining such Ga-rich growth condition in the active region with polarization field enhanced carrier injection layers, deep UV-LEDs emitting at 273 nm were obtained with output power of 0.35 mW and 1.3 mW at 20 mA continuous wave and 100 mA pulsed drive current, respectively. The maximum external quantum efficiency was 0.4%. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559842]