Efficiency Dependence on Degree of Localization States in GaN-Based Asymmetric Two-Step Light-Emitting Diode With a Low Indium Content InGaN Shallow Step

GaN-based asymmetric two-step light-emitting diodes (LEDs) with a low indium content (LIn) InGaN shallow step was proposed and fabricated. It was found the LIn–InGaN shallow step can significantly enhance phase separation and/or inhomogeneous indium distribution in the active $\hbox{In}_{0.27}{\hbox {Ga}}_{0.73}\hbox{N}$ layer. By inserting an $\hbox{In}_{0.08}{\hbox {Ga}}_{0.92}\hbox{N}$ shallow step, it was found that we can enhance LED output power by a factor of 2.27 with an injection current of 20 mA.