High External Quantum Efficiency Green Light Emitting Diodes on Stress-Manipulated AlNO Buffer Layers

We demonstrated high-brightness InGaN/GaN green light emitting diodes (LEDs) with ex-situ sputtered stress-manipulated AlNO buffer on 4-inch patterned sapphire substrates. The lattice constant of the AlNO buffer was adjusted by oxygen flow. As a result, the dislocation density and the in-plane compressive stress caused by lattice mismatch were greatly reduced, while the interface quality of the InGaN/GaN multiple quantum wells and the uniformity of the indium composition were greatly improved. At 20A/cm(2), the external quantum efficiency and wall plug efficiency of the 526.4-nm-green LEDs grown on the sputtered AlNO buffer reached 46.1% and 41.9%, which were both higher than reported values.