Study of InGaN–GaN Light-Emitting Diodes With Different Last Barrier Thicknesses

This work reports a theoretical and experimental study on the device performance of blue InGaN-GaN light-emitting diodes (LEDs) with different last barrier thicknesses. The experimental results show that the employment of a 25-nm-thick p-type GaN last barrier in GaN LEDs can improve the light output power from 35.6 to 40.2 mW at 50 mA. By using advanced device simulation, it is shown that the effective energy barrier created by the p-type AlGaN electron blocking layer (EBL) is significantly decreased due to the band bending at the interface between GaN last barrier and AlGaN EBL. The use of a p-type GaN last barrier before the growth of AlGaN EBL can provide a higher energy barrier to suppress the electron overflow and then enhance the light output power.