Novel UV devices on high-quality AlGaN using grooved underlying layer

A grooved Al0.25Ga0.75N underlying layer on an AlN-coated sapphire substrate was used to grow crack free and low dislocation density Al0.25Ga0.75N to successfully realize high-performance UV A light emitters. A light-emitting diode grown on a grooved AlGaN underlying layer exhibited an output power of 12 mW at a DC current of 50 mA for a peak emission wavelength of 345 nm with an external quantum efficiency of 6.7%, which is the highest to date in this wavelength region. We also fabricated UV A laser diodes with an emission wavelength of 356 nm at a pulsed injection current of 414 mA.