Analysis of the various light extraction efficiency enhancement mechanisms for the GaN-based light emitting diodes (LEDs) was investigated. Experiments utilized the imprinting technique to fabricate pyramid and inverted pyramid microstructures. Roughness treatment was then integrated with these imprinting structures on patterned sapphire substrate (PSS) LEDs. An approximate 33% improvement in light output power was obtained using the pyramid profile when compared with the planar LED. This was nearly 15% higher than that of the inverted pyramid profile. The roughness effect provided an approximate 5% efficiency enhancement. The total light enhanced efficiency increased to 85.9% by integrating the imprinting pyramid structure, PSS, and surface roughness.
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