Investigation of GaN-based vertical-injection light-emitting diodes with GaN nano-cone structure by ICP etching

The GaN-based thin-film vertical-injection LEDs (VLEDs) with GaN nano-cone structures are fabricated and presented. Under the process conditions of fixed Cl2/Ar flow rate of 10/25 sccm and ICP/bias power of 200/200 W, the GaN nano-cone structures are self-assembly formed with variable density of 1.5 × 107 to 1.4 × 109 cm−2 and variable depth of 0.56–1.34 μm when varying the ICP chamber pressure. At a driving current of 350 mA and with chip size of 1 mm × 1 mm, the light output power of our thin-film LED with a specific GaN nano-cone structure reaches 224 mW which is enhanced by 160% when compared with the output power of conventional VLED. In addition, the corresponding light radiation pattern shows much higher light intensity due to the strong light scattering effect by the formed nano-cone structure.