Improving hole injection with the polarization effect for AlGaN-based deep ultraviolet light-emitting diodes

Abstract

The low hole injection efficiency in the active region of AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) is attributed to the high ionization energy of acceptor magnesium, which has been widely acknowledged. In this paper, the hole injection efficiency of AlGaN-based DUV LEDs is effectively enhanced by utilizing the polarization effect in quantum wells. By appropriately increasing the thickness of the quantum well, the polarization electric field can be utilized to increase the mean free path of holes and enhance hole concentration in the active region. This approach effectively boosts hole concentration and promotes a more uniform distribution of holes in the quantum wells. Therefore, the DUV LED had a high internal quantum efficiency of 70.3% and optical power of 56.02 W/cm2 when the quantum well thickness is 5 nm. It is noteworthy that the strong quantum confined stark effect can cause electron and hole wave functions to separate, leading to a decrease in LED performance when quantum wells exceed a certain thickness.