title: High efficiency GaN-based light emitting diode with nano-patterned ZnO surface fabricated by wet process.
abstract: The improvement of the optical output power of GaN-based light emitting diodes (LEDs) was achieved by a novel bi-layer transparent top electrode scheme. The proposed bi-layer structure is composed of a Ga-doped ZnO layer with nano-patterns obtained solely by wet etching process and an Indium Tin Oxide p-type transparent conducting electrode layer. We employed various wet-etching conditions to maximize light extraction efficiency and it was observed that the crystal morphologies of nano-patterns and optoelectronic properties are dependent on etching duration. Because of ITO under GZO layer, the current spreading was not affected even after formation of nano-patterned surface on the GZO layer by wet etching. Consequently, an enhancement of as high as 43.1% in optical output power at an injection current of 100 mA for the LED with nano-patterns wet-etched by 0.025% HCl for 30 seconds was realized without significant degradation in electrical property when compared to a reference LED.
authors.affiliation: Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung-Si, Gyeonggi-Do, 429-793, Korea.
authors.forename: Semi
authors.initials: S
authors.lastname: Oh
authors.forename: Sung-Nam
authors.initials: SN
authors.lastname: Lee
authors.forename: Soohaeng
authors.initials: S
authors.lastname: Cho
authors.forename: Kyoung-Kook
authors.initials: KK
authors.lastname: Kim