Low-resistance Al-based reflectors for high-power GaN-based flip-chip light-emitting diodes

摘要

We report on the formation of high-quality p-type Al-based ohmic reflectors using Ag (3 nm)/indium tin oxide (ITO)(100 nm) interlayers for use in high-power flip-chip light-emitting diodes (LEDs). The Ag/ITO interlayers are first annealed at temperatures of 530 and 630℃ for 1 min in air, after which Al reflectors (200 nm thick) are deposited and subsequently annealed at 330℃ for 5 min in a vacuum. It is shown that the annealed Ag/ITO/Al contacts give specific contact resistances as low as ～10~5 Ω cm~(-2) and reflectance of ～85% at a wavelength of 460 nm, which are much better than those of oxidized Ni/Au schemes. LEDs fabricated with the annealed Ag/ITO/Al p-type electrodes give forward-bias voltages of 3.29-3.37 V at injection current of 20 mA.