Plasmonic-Enhanced Light Absorption in Periodic Silicon Structures: The Effect of Inter-Island Distance

Absorption spectra of Si/SiO 2 /Si structure with highly doped silicon layers are simulated with Finite Difference Time Domain (FDTD) as a function of periodicity of surface islands. The effect of multiple resonance is studied for different inter-island distances. A wide band (>12 µm) of high light absorption (>70%) is registered for a structure with a period of 8 μm and an inter-island distance of 3 μm. It is revealed for the spectral range of 10–20 μm that the reduction of the inter-islands distance shifts the absorption peak position to the region of longer waves and results in the growth of the absorption level.