title: Glass-Based Transparent Conductive Electrode: Its Application to Visible-to-Ultraviolet Light-Emitting Diodes.
abstract: Nitride-based ultraviolet light-emitting diodes (UV LEDs) are promising replacements for conventional UV lamps. However, the external quantum efficiency of UV LEDs is much lower than for visible LEDs due to light absorption in the p-GaN contact and electrode layers, along with p-AlGaN growth and doping issues. To minimize such absorption, we should obtain direct ohmic contact to p-AlGaN using UV-transparent ohmic electrodes and not use p-GaN as a contact layer. Here, we propose a glass-based transparent conductive electrode (TCE) produced using electrical breakdown (EBD) of an AlN thin film, and we apply the thin film to four (Al)GaN-based visible and UV LEDs with thin buffer layers for current spreading and damage protection. Compared to LEDs with optimal ITO contacts, our LEDs with AlN TCEs exhibit a lower forward voltage, higher light output power, and brighter light emission for all samples. The ohmic transport mechanism for current injection and spreading from the metal electrode to p-(Al)GaN layer via AlN TCE is also investigated by analyzing the p-(Al)GaN surface before and after EBD.
authors.affiliation: School of Electrical Engineering, Korea University , Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
authors.forename: Tae Ho
authors.initials: TH
authors.lastname: Lee
authors.affiliation: School of Electrical Engineering, Korea University , Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
authors.forename: Kyeong Heon
authors.initials: KH
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Korea University , Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
authors.forename: Byeong Ryong
authors.initials: BR
authors.lastname: Lee
authors.affiliation: School of Electrical Engineering, Korea University , Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
authors.forename: Ju Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.
authors.forename: E Fred
authors.initials: EF
authors.lastname: Schubert
authors.affiliation: School of Electrical Engineering, Korea University , Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
authors.forename: Tae Geun
authors.identifier: 0000-0001-6211-1134
authors.initials: TG
authors.lastname: Kim
keywords: conducting filament; light-emitting diode; transparent conductive electrode; ultraviolet; wide-bandgap