Enhanced performance of a GaN-based LED prepared by an anodized aluminum oxide-nanoporous pattern sapphire substrate

A new approach to fabricate a GaN light-emitting diode (LED), grown on an anodized aluminum oxide-nanoporous pattern sapphire substrate (AAO-NPSS), is studied. An AAO film is used as a dry etching mask to transfer nanoporous patterns on the sapphire substrate. Because of the use of AAO-NPSS, threading dislocations could be reduced and air voids would be formed to reflect downward photons toward top direction. As compared with a conventional LED, at 20 mA, the AAO-NPSS-based device exhibits 52.8% enhancements of light output power. The reduced leakage current and lower turn-on voltage are also achieved. Therefore, the use of AAO-NPSS structure could effectively improve the crystalline quality and light extraction efficiency, which certainly leads to the enhanced performance of GaN LEDs.