Study on Injection Efficiency in InGaN/GaN Multiple Quantum Wells Blue Light Emitting Diodes

The dependence of the electrical efficiency on the injection current was studied in detail in InGaN/GaN multiple quantum wells (MQWs) blue light emitting diodes. When the InGaN quantum well thickness increased from 2 to 3.5 nm, or the Al component in p-AlGaN changed from 0.1 to 0.2, it was found that the electrical efficiency decreased dramatically, while a thin Mg-doped GaN layer inserted between p-AlGaN and MQWs with optimized Mg concentration can enhance the electrical efficiency effectively. Analysis shows that the injection efficiency was dramatically affected by the interface states due to the strong stress at the interface between p-AlGaN blocking layer and MQWs active region and the capability of electrons arriving at the interface.