Role of metallic absorption on enhancing the light emitting efficiency by plasmonic gratings

Due to the adoption of the metallic materials in the surface-plasmon-based light emitting diodes (SP-LEDs), strong absorption of the metal can result in the dissipation of the most photons in the form of thermal energy. In order to investigate the role of the metallic absorption in the SP-LEDs, by means of a series of computational examples of our proposed structure, the effects of several features on the absorptivity of the metal and the light extraction efficiency (LEE) of the chips have been analyzed in detail. The results indicate that the chips with combined metallic and dielectric gratings can exhibit relatively the highest LEE, whereas the absorption of the metal in the chips is very strong, and the absorptivity is several times of LEE. It is concluded that to reduce the absorption and keep high light extraction, proper structure in which the odd mode of surface plasmons can be stimulated at the desired wavelength should be used. In addition, the hexagonal gratings show relatively larger light extraction enhancement and stronger absorption than the rectangular ones.