High extraction efficiency GaN-based light-emitting diodes on embedded SiO₂ nanorod array and nanoscale patterned sapphire substrate

In this paper, GaN-based LEDs with a nanoscale patterned sapphire substrate (NPSS) and a SiO₂ photonic quasicrystal (PQC) structure on an n-GaN layer using nanoimprint lithography are fabricated and investigated. The light output power of LED with a NPSS and a SiO₂ PQC structure on an n-GaN layer was 48% greater than that of conventional LED. Strong enhancement in output power is attributed to better epitaxial quality and higher reflectance resulted from NPSS and PQC structures. Transmission electron microscopy images reveal that threading dislocations are blocked or bended in the vicinities of NPSS layer. These results provide promising potential to increase output power for commercial light emitting devices.