title: Light outcoupling effect in GaN light-emitting diodes via convex microstructures monolithically fabricated on sapphire substrate.
abstract: GaN-based light-emitting diode (LED) was fabricated on the sapphire substrate with monolithic convex microstructures (CMs) array. Using confocal scanning electroluminescence (EL), we have directly observed the strong outcoupling phenomenon of the light confined in a LED via the CMs array. This outcoupled light could be efficiently converged on the convex center through consecutive reflections at the flat area and the curved slant area of the CMs array. Compared to the conventional LED, the ray tracing simulation and far field EL results of the LED with a CM array showed efficient light extraction toward the top surface, i.e., 0-5, 40-45 and 60-65 degree by the outcoupling effect. We conclude that the outcoupled optical path via CMs is the dominant factor of the enhanced light extraction in the LED with a CM array.
authors.affiliation: School of Semiconductor & Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 561-756, South Korea.
authors.forename: Tae Su
authors.initials: TS
authors.lastname: Oh
authors.forename: Hyun
authors.initials: H
authors.lastname: Jeong
authors.forename: Yong Seok
authors.initials: YS
authors.lastname: Lee
authors.forename: Ah Hyun
authors.initials: AH
authors.lastname: Park
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Seo
authors.forename: Hun
authors.initials: H
authors.lastname: Kim
authors.forename: Kang Jea
authors.initials: KJ
authors.lastname: Lee
authors.forename: Mun Seok
authors.initials: MS
authors.lastname: Jeong
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Suh