Optimization of Ni/Ag-Based Reflectors to Improve the Performance of 273 nm Deep Ultraviolet AlGaN-Based Light Emitting Diodes
- Authors
- Sim, Kee-Baek; Kim, Su-Kyung; Lee, Hwa-Seub; Lee, Sang-Youl; Seong, Tae-Yeon; Amano, Hiroshi
- Issue Date
- 1-4월-2021
- Publisher
- ELECTROCHEMICAL SOC INC
- Citation
- ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY, v.10, no.4
- Indexed
- SCIE
SCOPUS
- Journal Title
- ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
- Volume
- 10
- Number
- 4
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/128272
- DOI
- 10.1149/2162-8777/abf49b
- ISSN
- 2162-8769
- Abstract
- We optimized Ni/Ag-based p-type reflectors for the improvement of efficiency of 273 nm deep ultraviolet (DUV) AlGaN-based flip-chip light emitting diodes (FCLEDs). The Ni(3 nm)/Ag(5-15 nm)/Al/Ni and Ni(25-50 nm)/Ag/Ni contacts exhibited higher reflectance (36.4-39.5%) at 273 nm than reference Ni(5 nm)/Au(5 nm)/Al/Ni contact (26.1%). The Ni(3 nm)/Ag/Al(200 nm)/Ni(20 nm) and Ni/Ag(200 nm)/Ni(20 nm)-based FCLEDs gave forward voltages in the rage of 6.93-7.11 V and 5.5-6.28 V at 20 mA, respectively, whereas the Ni/Au-based sample showed 6.35 V. Further, the Ni(3 nm)/Ag(10 nm)/Al/Ni-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples exhibited 4.85% and 13.4% larger output power at 1.2 W than the reference sample. The Ni(3 nm)/Ag(10 nm)-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples produced 5.6% and 8.5% higher peak external quantum efficiency than the reference sample. It was further shown that the Ni(3 nm)/Ag(10 nm)/Al/Ni-based and Ni(50 nm)/Ag(200 nm)/Ni-based samples experienced less efficiency droop (namely, 27.9 and 26.4%, respectively) than the reference sample (31.4%). Based on the scanning transmission electron microscopy and X-ray photoemission spectroscopy results, the ohmic formation mechanism is described and discussed.
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