Improving the Thermal Stability of Ag Ohmic Contacts for GaN-based Vertical Light-emitting Diodes with a Cu Capping Layer
- Authors
- Joo, Min-Kyoung; Jung, Se-Yeon; Seong, Tae-Yeon
- Issue Date
- 3월-2012
- Publisher
- KOREAN PHYSICAL SOC
- Keywords
- LEDs; GaN; Ag reflectors; Cu capping layer; Ohmic contacts
- Citation
- JOURNAL OF THE KOREAN PHYSICAL SOCIETY, v.60, no.5, pp.857 - 861
- Indexed
- SCIE
SCOPUS
KCI
- Journal Title
- JOURNAL OF THE KOREAN PHYSICAL SOCIETY
- Volume
- 60
- Number
- 5
- Start Page
- 857
- End Page
- 861
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/105341
- DOI
- 10.3938/jkps.60.857
- ISSN
- 0374-4884
- Abstract
- We investigated the effect of a 20-nm-thick Cu capping layer on the electrical and the optical properties of Ag contacts (200 nm thick) in order to form thermally stable and low-resistance p-type ohmic reflectors for high-performance vertical light-emitting diodes (LEDs). The Ag/Cu contacts give a specific contact resistance of 6.7 x 10(-4) Omega cm(2) and a reflectance of similar to 78% at a wavelength of 460 nm when annealed at 400 degrees C for 1 min in air, which are better than that of Ag only contacts. Blue LEDs fabricated with the Ag/Cu contacts give a forward voltage of 2.90 V at an injection current of 20mA, which is lower than that (2.97 V) of LEDs with Ag only contacts. The LEDs with the 400 degrees C-annealed Ag/Cu contacts exhibit similar to 27% higher output power (at 20 mA) than LEDs with the 400 degrees C-annealed Ag only contacts. X-ray photoemission spectroscopy examinations were carried out to describe the improved electrical behaviour of the Ag/Cu contacts.
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