GaN-based LEDs Fabricated on Cone-Shaped Patterned Sapphire Substrates with Modified Top-Tip

GaN-based light emitting diodes (LEDs) structure were grown on the cone-shaped patterned sapphire substrates (PSSs) using metalorganic chemical vapor deposition. To improve the crystal quality of nitride epilayer and optoelectronic performance of LED device, the top-tip cone shapes of PSSs were further modified by wet etching. Using wet etching process, some dry-etched induced damage on substrate surface created during the PSS fabrication process could be removed, resulting in higher crystal quality of epilayer and better device performance. In comparison to the LEDs grown on the conventional sapphire substrate (CSS) and cone-shaped PSS without wet etching, the LED prepared on the cone-shaped PSS with wet etching for 3 minhad 55% and 10% improvement in output power at a driven current of 350 mA, respectively. It reveals that the technique of the modification in PSS shape is potentially useful in LEDs application