Ultraviolet light emitting diodes

AlGaN-based ultraviolet light-emitting diodes grown on AlN epilayers

AlGaN-based deep-ultraviolet light-emitting diode (LED) structures, which radiate light at 305 and 290 nm, have been grown on sapphire substrates using an AlN epilayer template. The fabricated devices have a circular geometry to enhance current spreading and light extraction. Circular UV LEDs of different sizes have been characterized. It was found that smaller disk LEDs had higher saturation o...

III-nitride ultraviolet light-emitting diodes with delta doping

Nitride deep-ultraviolet light-emitting diodes with microlens array

We report on the fabrication of 280-nm AlGaN-based deep-ultraviolet light-emitting diodes sUV LEDsd on sapphire substrates with an integrated microlens array. Microlenses with a diameter of 12 mm were fabricated on the sapphire substrate by resist thermal reflow and plasma dry etching. LED devices were flip-chip bonded on high thermal conductive AlN ceramic submounts to improve the thermal diss...

III-nitride blue and ultraviolet photonic crystal light emitting diodes

We present results on enhancement of 460 nm blue and 340 nm UV optical power output in III-nitride light emitting diodes ~LEDs! using photonic crystals ~PCs! under current injection. Triangular arrays of the PCs with diameter/periodicity of 300/700 nm were patterned using electron-beam lithography and inductively coupled plasma dry etching. The total power at 20 mA of 3003300 mm unpackaged LED ...

Degradation of AlGaN-based ultraviolet light emitting diodes

Aging the LEDs by driving at high current, results in the decrease of optical power proportional to the reciprocal square route of stress time. With aging time, change in the current–voltage characteristics indicates decrease of the current at low voltage below the light emission threshold, decrease of the forward voltage drop at high currents and usually no change in the series resistance. No ...