title: Enhancement of light output power in GaN-based light-emitting diodes using hydrothermally grown ZnO micro-walls.
abstract: We report on the efficiency enhancement in GaN-based light-emitting diodes (LEDs) using ZnO micro-walls grown by a hydrothermal method. The formation of ZnO micro-walls at the indium tin oxide (ITO) border on the LED structure is explained by the heterogeneous nucleation effect. The light output power of LEDs with ZnO micro-walls operated at 20 mA was found to increase by approximately 30% compared to conventional LEDs. Moreover, the finding of nearly the same current-voltage characteristics of GaN-based LEDs with and without a ZnO micro-wall shows that the ZnO micro-wall does not influence the electrical properties of the device but only leads to an increase in the light extraction efficiency. From the confocal scanning electroluminescence results, we confirm that ZnO micro-walls enhance the light output power via the photon wave-guiding effect.
authors.affiliation: Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju, South Korea.
authors.forename: Hyun
authors.initials: H
authors.lastname: Jeong
authors.forename: Yong Hwan
authors.initials: YH
authors.lastname: Kim
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Seo
authors.forename: Hong Seok
authors.initials: HS
authors.lastname: Lee
authors.forename: Jun Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Suh
authors.forename: Mun Seok
authors.initials: MS
authors.lastname: Jeong
mesh_terms: D003460:Crystallization; D004563:Electrochemistry / Q000379:methods; D004583:Electrons; D004867:Equipment Design; D005708:Gallium / Q000737:chemistry; D008027:Light; D049449:Luminescence; D018613:Microscopy, Confocal / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D017785:Photons; D020349:Surface Plasmon Resonance; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: C473348:gallium nitride; D005708:Gallium; D015034:Zinc Oxide