Carrier transport barrier in AlGaN-based deep ultraviolet LEDs on offcut sapphire substrates

AlGaN-based light-emitting diodes(LEDs) on offcut substrates enhance radiative emission via forming carrier localization centers in multiple quantum wells(MQWs). This study introduces the carrier transport barrier concept, accessing its impact on the quantum efficiency of LEDs grown on different offcut sapphire substrates. A significantly enhanced internal quantum efficiency(IQE) of 83.1% is obtained from MQWs on the 1° offcut sapphire, almost twice that of the controlled 0.2° offcut sample. Yet, 1° offcut LEDs have higher turn-on voltage and weaker electroluminescence than 0.2° ones. Theoretical calculations demonstrate the existence of a potential barrier on the current path around the step-induced Ga-rich stripes.Ga-rich stripes reduce the turn-on voltage but restrict sufficient driving current, impacting LED performance.