Submilliwatt Operation of AlInGaN Based Multifinger-Design 315 nm Light Emitting Diode (LED) over Sapphire Substrate

We report on sub-milliwatt operation of ultra-violet light emitting diodes on sapphire with a peak emission wavelength of 315 nm having quaternary AlInGaN multiple quantum well (MQW) active region. A significant increase in the device-emitted power was achieved using an interdigitated finger geometry design, which reduces the differential resistance and eliminates current crowding. The flip-chip mounting of the diced chips with sapphire substrates improves thermal management and increases the light extraction efficiency from the device active area. For 315 nm emission an optical power as high as 0.23 mW was obtained with 800 mA pulsed pumping current.