Characteristics of InGaN-based light-emitting diodes on patterned sapphire substrates with various pattern heights

The optical and electrical characteristics of InGaN-based blue light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different pattern heights and on planar sapphire by atmospheric-pressure metal-organic chemical vapor deposition were investigated. Compared with planar sapphire, it was found that the LED electroluminescence intensity is significantly enhanced on PSSs with pattern heights of 0.5 (21%), 1.1 (57%), 1.5 (81%), and 1.9 (91%)μm at an injected current of 20mA. The increased light intensity exhibits the same trend in a TracePro simulation. In addition, it was also found that the level of leakage current depends on the density of V-shape defects, which were measured by scanning electron microscopy.