247 nm Ultra-Violet Light Emitting Diodes

We report on AlGaN-based ultraviolet light emitting diodes with emission at the wavelengths as short as 247 nm. Migration-enhanced metal organic chemical vapor deposition technique allowed us to improve the material quality. The phonon energy gap engineering approach was used to optimize these UV sources and achieve continuous-wave regime at turn-on voltages lower than 8 V at 20 mA current. Power levels of 0.3 mW were achieved for the packaged devices driven at 90 mA DC current. In the pulse operation 9 mW output power was measured at 1.4 A current. The peak to noise emission ratio was close to 400 at cw current in excess of 20 mA.