Luminescence efficiency of InGaN multiple-quantum-well ultravioletlight-emitting diodes

The electroluminescence efficiency of In0.06Ga0.94N∕GaN multiple-quantum-well UV light-emitting diodes (LEDs) with emission wavelength of 400nm has been investigated and compared with blue (470nm) LEDs. Based on their injection current-dependent characteristics under dc and pulsed operation, it can be concluded that carrier overflow is the dominant factor that affects the external quantum efficiency of UVLED before thermal effects take over. It is experimentally shown that increasing the number of quantum wells is necessary to alleviate the carrier overflow issue and improve the luminescence efficiency of the UVLEDs.