Enhanced performance of InGaN-based light-emitting diodes grown on volcano-shaped patterned sapphire substrates with embedded SiO₂

This paper describes highly efficient InGaN-based light-emitting diodes (LEDs) grown on volcano-shaped patterned sapphire substrates with embedded SiO₂ (SVPSS). Raman spectroscopy and transmission electron microscopy revealed that the LEDs grown on the SVPSS had high internal quantum efficiency resulting from relaxed compressive strain and fewer threading dislocations in the GaN epitaxial layers. Experimentally measured data and ray-tracing simulations suggested that the enhancement in the light extraction efficiency was due to the light scattering effect arising from the conical air voids and the gradual refractive index matching resulting from the embedded SiO₂. Compared with a conventional LEDs operated at an injection current of 350 mA, the light output power from our LED grown on SVPSS was increased by 72%.