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 × 10 -4 Ωcm 2 and a reflectance of ~78% at a wavelength of 460 nm when annealed at 400 °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 °C-annealed Ag/Cu contacts exhibit ~27% higher output power (at 20 mA) than LEDs with the 400 °C-annealed Ag only contacts. X-ray photoemission spectroscopy examinations were carried out to describe the improved electrical behaviour of the Ag/Cu contacts.
Original language | English |
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Pages (from-to) | 857-861 |
Number of pages | 5 |
Journal | Journal of the Korean Physical Society |
Volume | 60 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2012 Mar |
Keywords
- Ag reflectors
- Cu capping layer
- GaN
- LEDs
- Ohmic contacts
ASJC Scopus subject areas
- Physics and Astronomy(all)