title: High efficiency white LEDs with single-crystal ZnO current spreading layers deposited by aqueous solution epitaxy.
abstract: Heteroepitaxial ZnO transparent current spreading layers with low sheet resistances were deposited on GaN-based light emitting diodes using aqueous solution phase epitaxy at temperatures below 90°C. The performance of the LEDs was analyzed and compared to identical devices using electron-beam evaporated indium tin oxide transparent current spreading layers. White LEDs with ZnO layers provided high luminous efficacy–157 lm/W at 0.5A/cm2, and 84.8 lm/W at 35A/cm2, 24% and 50% higher, respectively, than devices with ITO layers. The improvement appears to be due to the enhanced current spreading and low optical absorption provided by the ZnO.
authors.affiliation: Department of Materials, University of California, Santa Barbara, California 93106, USA.
authors.forename: Arthur H
authors.initials: AH
authors.lastname: Reading
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Richardson
authors.forename: Chih-Chien
authors.initials: CC
authors.lastname: Pan
authors.forename: Shuji
authors.initials: S
authors.lastname: Nakamura
authors.forename: Steven P
authors.initials: SP
authors.lastname: DenBaars
mesh_terms: D003116:Color; D003460:Crystallization; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting / Q000295:instrumentation*; D012666:Semiconductors; D012996:Solutions; D014867:Water / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D015034:Zinc Oxide