Improved Light Extraction Efficiency of InGaN-Based Light-Emitting Diodes with Patterned n-GaN Substrate

We improved the light extraction efficiency of InGaN-based light-emitting diodes (LEDs) in which an n-type GaN layer was patterned onto a sapphire substrate with nano-sized SiO2 columns. Indium tin oxide thin layer deposition on a SiO2 layer followed by wet etching gives rise to oxide self-assembled clusters of 100-400 nm size and a subsequent SiO2 etching with an oxide mask results in SiO2 columns on an n-type GaN layer. The output power of the patterned n-GaN substrate (PNS) LED shows a 1.33 time increase compared with that of a normal LED without an n-GaN pattern when the total output power emitted in all directions from the packaging LED was measured under a current injection of 20 mA. The increase in output power from the PNS LED depends on the size of the SiO2 columns on the n-type GaN substrate.