Double-sided hemispherical pattern design on patterned sapphire substrate of GaN-based LEDs

In this paper, we established a optical model and optimized a double-sided hemispherical patterned sapphire substrate (PSS) for highly efficient flip-chip GaN-based light emitting diodes (LEDs). A simulation is conducted to study how light extraction efficiency changes with the change in the parameters of the unit hemisphere for LEDs fabricated on hemispherical PSS. Results show that the light extraction efficiency of flip-chip LEDs can be enhanced by the optimized hemispherical PSS by over 50% and is approximately 115% higher than that of flip-chip LEDs with non-PSS.