Investigation of GaN-Based Light-Emitting Diodes Grown on Patterned Sapphire Substrates by Contact-Transferred and Mask-Embedded Lithography

The influences of pattern size and etching depth of patterned sapphire substrates (PSSs) on crystal quality and light output power of light-emitting diodes (LEDs) were investigated by contact-transferred and mask-embedded lithography. The present results indicate that a smaller pattern size facilitates superior light extraction efficiency. However, a suitable pattern size and etching depth should be chosen to obtain the highest quality of GaN film. In comparison with the conventional sapphire substrate, the largest light output enhancement (similar to 28.9%) was observed when the pattern diameter and the etching depth of PSS were 400 and 400 nm, respectively. (C) 2011 The Japan Society of Applied Physics