Design and measurement of long-wavelength infrared antireflection coating multi-layers of SiO2 and Si3N4 on silicon window by Macleod software and FTIR technique

In this paper, we have proposed an antireflection coating multi-layers of SiO
₂
/Si
₃
N
₄
on silicon window, suitable for the infrared range of 8~12 μm. The 4-layers coating (2-periods of SiO
₂
/Si
₃
N
₄
) with optimized thicknesses was designed using Essential Macleod program developed from Thin Film Center Inc. Based on the proposed long-wavelength infrared silicon-based window by simulation, the samples were also fabricated by physical vapor deposition technique to characterize and achieve the best possible agreement by FTIR spectroscopy. It was found that, in the wavelength range of 8~12 μm, the average transmittance of the double-side coated sample increases by about 39% compared to uncoated silicon window and its maximum reaches about 98% at 9 μm.