Enhanced Performance of GaN/InGaN Multiple Quantum Well LEDs by Shallow First Well and Stepped Electron-Blocking Layer

This work analyzes the effect of incorporating a shallow first well and a two-step electron-blocking layer (EBL) on the performance of an InGaN/GaN rectangular multiple quantum well LED using well-calibrated numerical simulator SILVACOATLAS. The results show 78% improvement in output power of the proposed LED structure in comparison with the conventional structure at 150 mA injection current. In addition, the droop in internal quantum efficiency (IQE) for the proposed LED structure reduces to 29% from 54% which is observed in conventional structure. The simulation study reveals that the shallow first well facilitates to reduce the effective blocking provided by the preceding GaN layer to the injected electrons, thereby increasing the electron injection. In addition, the stepped electron-blocking layer raises the energy barrier for electrons at the EBL causing better confinement of electrons compared to conventional structure. The stepped EBL also decreases the effective energy barrier for holes significantly, thereby aiding better injection of holes into the multiple quantum well light-emitting region. Consequently, carrier concentrations in the active region of the proposed structure increase, thereby enhancing its output power at high input current.