There is a rapidly growing demand for highly efficient ultraviolet (UV) light sources for a wide variety of applications. In particular, state-of-the-art AlGaN deep UV light-emitting diodes (DUV LEDs) exhibit inadequately low external quantum efficiencies (EQEs). The low efficiencies are attributed to the inherent material properties of high-Al-content AlGaN including strained epitaxial layers, low carrier concentrations, and strong transverse magnetic (TM)-polarized light emission. Extensive efforts have been made to tackle these challenging issues and technological developments have been achieved and enabled the fabrication of reasonable EQE LEDs. In this review, recent advances in the growth of high-quality AlGaN epitaxial layers, transparent and reflective ohmic contacts, and light extraction for AlGaN-based UV LEDs are reviewed.
Bibliographical noteFunding Information:
This work was supported by LG Innotek, Co., Ltd. and the development of R&D professionals on LED convergence lighting for shipbuilding/marine plant and marine environments (project No: N0001363) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).
© The Author(s) 2017.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials