title: An elegant route to overcome fundamentally-limited light extraction in AlGaN deep-ultraviolet light-emitting diodes: Preferential outcoupling of strong in-plane emission.
abstract: While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic polarized emission pattern of AlGaN quantum wells. The sidewall-emission-enhanced DUV LED breaks through the fundamental limitations caused by the intrinsic properties of AlGaN, thus shows a remarkable improvement in light extraction as well as operating voltage. Furthermore, an analytic model is developed to understand and precisely estimate the extraction of DUV photons from AlGaN DUV LEDs, and hence to provide promising routes for maximizing the power conversion efficiency.
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.
authors.forename: Dong Yeong
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.
authors.forename: Jun Hyuk
authors.initials: JH
authors.lastname: Park
authors.affiliation: Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA.
authors.forename: E Fred
authors.initials: EF
authors.lastname: Schubert
authors.affiliation: Advanced Development Team, LED Business, Samsung Electronics, Yongin 446-920, Korea.
authors.forename: Jungsub
authors.initials: J
authors.lastname: Kim
authors.affiliation: Advanced Development Team, LED Business, Samsung Electronics, Yongin 446-920, Korea.
authors.forename: Jinsub
authors.initials: J
authors.lastname: Lee
authors.affiliation: Advanced Development Team, LED Business, Samsung Electronics, Yongin 446-920, Korea.
authors.forename: Yong-Il
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Advanced Development Team, LED Business, Samsung Electronics, Yongin 446-920, Korea.
authors.forename: Youngsoo
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea.
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Kim