The light extraction enhancement of freestanding GaN-based flip-chip light-emitting diodes(FSFCLEDs)using two-step roughening methods is investigated.The output power of LEDs fabricated by using one-step and two-step roughening methods are compared.The results indicate that two-step roughening methods show more potential for light extraction.Compared with flat FS-FCLEDs,the output power of FS-FCLEDs with a nanotextured hemisphere surface shows an enhancement of 90.7%.
The light extraction enhancement of freestanding GaN-based flip-chip light-emitting diodes (FS- FCLEDs) using two-step roughening methods is investigated. The output power of LEDs fabricated by using one-step and two-step roughening methods are compared. The results indicate that two-step roughening meth- ods show more potential for light extraction. Compared with flat FS-FCLEDs, the output power of FS-FCLEDs with a nanotextured hemisphere surface shows an enhancement of 90.7%.