We report the improved performance of InGaN/GaN-based light-emitting diodes (LEDs) through Ag reflectors combined with a Zn middle layer. It is shown that the Zn middle layer (5 nm thick) suppresses the agglomeration of Ag reflectors by forming ZnO and dissolving into Ag. The Ag/Zn/Ag contacts show a specific contact resistance of 6.2 × 10(-5) Ωcm(2) and reflectance of ~83% at a wavelength of 440 nm when annealed at 500 °C, which are much better than those of Ag only contacts. Blue LEDs fabricated with the 500 °C-annealed Ag/Zn/Ag reflectors show 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 annealed Ag only contacts. LEDs with the 500 °C-annealed Ag/Zn/Ag contacts exhibit 34% higher output power (at 20 mA) than LEDs with the annealed Ag only contacts.

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We investigate the effect of Ni insertion on the electrical and thermal properties of Ag-based reflectors for GaN-based light emitting diodes (LEDs). It is shown that after annealing at 500 °C, the surface of Ag only sample becomes significantly roughened due to agglomeration, whereas the surface of Ni-inserted Ag sample get roughened with elongated Ag hillocks on an ∼100-nm-thick Ag film. The Ni-inserted Ag contacts show higher reflectance (at 460 nm) than the Ag only sample after annealing at 500 °C. The 500-°C-annealed Ni-inserted Ag samples exhibit lower specific contact resistance than the annealed Ag only contacts. LEDs fabricated with the 500-°C-annealed Ni-inserted Ag contact give lower forward-bias voltage and series resistance as compared to those of LEDs with the 500-°C-annealed Ag only contact. The LEDs with the 500-°C-annealed Ni-inserted Ag contact exhibit 18% higher light output power (at 20 mA) than the LEDs with the Ag only contacts annealed at 500 °C. Based on the X-ray photoelectron spectroscopy and scanning electron microscopy results, the temperature dependence of the electrical characteristics of the Ni-inserted Ag contacts is described and discussed.

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We report the improved thermal stability of Ag reflectors for GaN-based light-emitting diodes (LEDs) using Ag nano-dots (∼65–∼190 nm in size). The nano-dot Ag samples show much higher reflectance than the Ag only samples. The annealed nano-dot Ag samples exhibit a smoother surface, where the grains contain numerous micro-twins. 〈111〉 texture becomes more dominantly evolved in the nano-dot Ag samples than in the Ag only samples after annealing. LEDs with the 300 °C-annealed nano-dot Ag reflectors exhibit 15%–36% higher output power (at 20 mA) than LEDs with the 300 and 400 °C-annealed Ag only reflectors.