Improved performance of AlGaN-based deep ultraviolet light-emitting diodes with nano-patterned AlN/sapphire substrates

• Published in: Applied physics letters Vol. 110; no. 19
• Main Authors: Lee, Donghyun, Lee, Jong Won, Jang, Jeonghwan, Shin, In-Su, Jin, Lu, Park, Jun Hyuk, Kim, Jungsub, Lee, Jinsub, Noh, Hye-Seok, Kim, Yong-Il, Park, Youngsoo, Lee, Gun-Do, Park, Yongjo, Kim, Jong Kyu, Yoon, Euijoon
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 08-05-2017
• Subjects: Aluminum gallium nitrides; Applied physics; Coalescing; Epitaxial growth; Epitaxial layers; Injection current; Light emitting diodes; Nanospheres; Organic light emitting diodes; Photons; Sapphire; Substrates; Ultraviolet radiation
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4983283

We demonstrated AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) with periodic air-voids-incorporated nanoscale patterns enabled by nanosphere lithography and epitaxial lateral overgrowth (ELO) on a 4-in. sapphire substrate. The nanoscale ELO improved the crystal quality of overgrown epitaxial layers at a relatively low growth temperature of 1050 °C and at small coalescence thickness less than 2 μm. The light output power of the DUV LED was enhanced significantly by 67% at an injection current of 20 mA. We attribute such a remarkable enhancement to the formation of embedded periodic air voids which cause simultaneous improvements in the crystal quality of epitaxial layers by ELO and light extraction efficiency enabled by breaking the predominant in-plane guided propagation of DUV photons.