The GaN-Based Light Emitting Diode Grown on Nanopattern Sapphire Substrate Prepared by Inductively Coupled Plasma Etching

We applied nanoimprint lithography to fabricate nanopattern sapphire substrate. Because the imprint resin cannot endure the inductively coupled plasma bombardment, we use Ni metal to replace the resin as our etching mask. And then, we tuned the parameters to achieve a depth-enough nanopattern sapphire substrate (200-500-nm thick). Then, light emitting diode (LED) structures were grown and the quality was characterized by X-ray diffraction and photoluminescence. The LED tester and integrating sphere were used to analyze the device property. The results could demonstrate that the film quality was improved with increasing etching depth. And, the compressive strain was also released with increasing etching depth. In addition, increasing etching depth could not only improve internal quantum efficiency, but also improve light extraction efficiency. Thus, the external quantum efficiency was enhanced. These evidences demonstrated that nanopatterned sapphire with deeper depth certainly enhanced performance of LEDs.