| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1554025 | Superlattices and Microstructures | 2012 | 7 Pages |
A Ru capping layer is employed to improve the thermal stability of Ag ohmic reflectors for high-power GaN-based light-emitting diodes (LEDs). The 20-nm-thick Ru capping layer is shown to be fairly effective in suppressing agglomeration by forming RuO2. The Ag/Ru contacts exhibit specific contact resistance of 8.1 × 10−5 Ω cm2 and reflectance of ∼89% at a wavelength of 450 nm when annealed at 500 °C for 1 min, which are much better than that of Ag only contacts. Blue LEDs fabricated with the 500 °C-annealed Ag/Ru contacts give a forward voltage of 2.98 V at an injection current of 20 mA, which is lower than that (3.02 V) of LEDs with the 500 °C-annealed Ag only contacts. LEDs with the 500 °C-annealed Ag/Ru contacts show 25% higher output power (at 20 mA) than LEDs with the 500 °C-annealed Ag only contacts. X-ray photoemission spectroscopy examinations are performed to describe the improved electrical performance of the Ag/Ru contacts.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A Ru capping layer used to improve the thermal stability of Ag ohmic reflectors. ► A Ru capping layer effectively suppresses the agglomeration of Ag reflector. ► Ag/Ru contact shows better electrical behavior than Ag only contact. ► LEDs with Ag/Ru contacts exhibit higher output power than LEDs with Ag only contact.
