Effects of the number of quantum wells on the performance of near-ultraviolet light-emitting diodes

Abstract

Near-ultraviolet light-emitting diodes (NUV LEDs) with different numbers of quantum wells (QWs) were grown by using metal-organic chemical vapor deposition (MOCVD) to investigate the effects of the number of QWs on the performance of NUV LEDs. With increasing number of QWs from 5 to 7 when using the same quantum well growth process, the normalized external quantum efficiencies (EQE) of 6- and 7-QW NUV LEDs are increased by 19.7% and 30.4%, respectively at 35 A/cm2 compared with that of the 5-QW NUV LED. As the number of QWs is increased from 5 to 7, the forward voltage at 350 mA is decreased from 3.94 V to 3.78 V and 3.77 V. The red shift of the peak wavelength is also decreased with increasing number of QWs. These data suggest that the improved EQE, the reduced peak wavelength shift, and the improved electrical characteristics are due to an increase in effective active volume with increasing number of QWs in NUV LEDs.