Broadband responsivity enhancement of Si photodiodes by a plasmonic antireflection bilayer

Randomly distributed plasmonic Ag nanoparticles (NPs) with various Sizes were fabricated by a reflow process to an island-shaped Ag thin-film deposited on a Si photodiode. These NPs contormally enclosed by an antireflective (AR)-type SiNx/SiO2 bilayer reveal significantly diminished reflectance in a broad wavelength (500 nm - 1100 nm) as compared to the cases of Ag NPs or SiO2 layer enclosing Ag NPs on the Si substrate. Accordingly, the tbrward scattering and the total reflection along with wide-angle interference in between the dielectric bilayer incorporating the Ag NPs induce highly increased light absorption in the Si substrate. The fabricated Si photodiode adopting the plasmonic AR bilayer shows the responsivity peak value of 0.72 A/W at 835 nm wavelength and significant responsivity enhancement up to 40% relative to a bare Si photodiode in a wavelength range of 500 nm to 1000 nm. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement