Electron overflow of AlGaN deep ultraviolet light emitting diodes

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 ...

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...

Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes

Enhancement of surface emission in deep ultraviolet AlGaN-based light emitting diodes with staggered quantum wells.

The optical polarization properties of staggered AlGaN-AlGaN/AlN quantum wells (QWs) are investigated using the theoretical model based on the k·p method. The numerical results show that the energy level order and coupling relation of the valence subband structure change in the staggered QWs and the trend is beneficial to TE polarized transition compared to that of conventional AlGaN/AlN QWs. A...

Distinct U-shape efficiency-versus-current curves in AlGaN-based deep-ultraviolet light-emitting diodes.

The efficiency of an AlGaN deep-ultraviolet light-emitting diode with peak emission wavelength of 285 nm is investigated as a function of current over a wide range of temperatures (110 K to 300 K). We find that the efficiency-versus-current curve exhibits unique and distinct features over the entire temperature range including three points of inflection. At low temperatures, the change in slope...