Numerical Simulation of GaN-Based LEDs With Chirped Multiquantum Barrier Structure

The authors report the numerical simulation of GaN-based light-emitting diodes (LEDs) with either a conventional AlGaN electron blocking layer (EBL), uniform multiquantum barrier (UMQB) structure, or chirped multiquantum barrier (CMQB) structure. It is found that the 102-meV effective barrier height simulated from the LED with CMQB structure is larger than those simulated from the LEDs with a UMQB structure (90 meV) and with conventional AlGaN EBL (60 meV). With the large effective barrier height, it is found that LEDs with a CMQB structure exhibit smaller leakage current. It is also found that the maximum internal quantum efficiencies are 0.703, 0.842, and 0.887, for the LEDs with conventional EBL, UMQB structure, and CMQB structure, respectively. In addition, it is found that forward voltages simulated from the LEDs with CMQB structure and with UMQB structure are both smaller than that simulated from the LED with conventional AlGaN EBL. These results also agree well with the experimental data.