High-Reflectance and Thermally Stable AgCu Alloy p-Type Reflectors for GaN-Based Light-Emitting Diodes

Improving the output power of near-ultraviolet InGaN/GaN-based light emitting diodes by enhancing the thermal and electrical properties of Ag-based reflector

“…In particular, for flip-chip and vertical geometry LEDs, high-reflectance metal-based reflectors, such as Ag and Al, have been widely used so as to increase the light extraction [4][5][6][7]. Although Al shows the highest optical reflectance in the UV region, but it is n-type electrode due to its small work function [8].…”

“…Ag is the most commonly used p-type reflectors for GaN-based LEDs. However, Ag experiences optical degradation when annealed at temperatures above 350°C [4,6]. Thus, to enhance the thermal property, various approaches, such as the use of interlayers, middle layers, capping layers, or Ag alloys, have been carried out.…”

“…Son and co-workers [16] reported that the Ru-capped Ag contacts showed low contact resistivity and high reflectance after annealing at 400°C in air. Ag alloys were also shown to be very effective in improving the thermal stability of Ag reflectors [6,17]. Kim and co-workers [6] reported that AgCu alloy reflectors exhibited better electrical and thermal properties than Ag only reflectors after annealing at 400°C.…”

Delayed <111> texture for improving the thermal stability of Ag reflectors for high-performance GaN-based light-emitting diodes

“…However, it suffers from agglomeration when annealed at temperatures above 300°C. To enhance the thermal reliability of Ag-based contacts, a variety of methods, such as overlayers [6][7][8], Ag alloys [9][10][11], interlayers [12][13][14] and inserted layers [15], have been used. For example, the use of overlayers, such as films of La [6], Zn [7] or Ru [8], was shown to considerably improve the thermal stability of Ag reflectors.…”

Nanometer sized Ni-dot/Ag/Pt structure for high reflectance of p-type contact metal in InGaN light emitting diodes

“…[1][2][3][4] For instance, in the vertical thin GaN LED structure, a silver coating may be applied to the surface of p-type GaN for high reflectivity. [5][6][7][8][9][10] This has an effect of improving the light extraction at the surface of n-GaN side, which surface faces the p-type GaN. Unfortunately, such solution faces difficulties arising from fabrication processes.…”