Design and preparation of high-transmittance broadband antireflection coatings with tailored refractive indices deposited by PECVD

The design and preparation of conventional optical films are mainly limited by the refractive indices of available materials. Here, a simple-operation antireflection coatings (ARCs) design method was developed based on the tailored refractive index characteristics of thin-film materials. High-transmittance, broadband (400-800 nm), three-layer single- and double-sided ARCs with tailored refractive indices and transmittances of 99.2% and 98.5%, respectively, were designed. The sensitivity of the ARCs system was simulated, which predicts the variable range of the transmittance affected by the random manufacturing errors in the refractive index (+/- 0.5%) and film thickness (+/- 2.5%) of each layer. The ARCs consisted of nonstoichiometric silicon oxynitride and silicon nitride films formed on glass substrates by PECVD techniques. The crystallite state, relative atomic concentration, and Si-centered tetrahedral phase Si-Si4(-(nu+eta))O(nu)N(eta) of each layer were determined. The morphology images of top and cross-section views and elemental mapping of ARCs were displayed. The designed and measured transmittances were compared; the average transmittance deviations of the single- and double-sided amorphous ARCs over the visible were 0.1% and 0.4%, respectively, which show good agreement. Furthermore, the reproducibility, repeatability, and stability of PECVD were evaluated. These results are detail discussed and are expected to serve as a reference for the preparation of optical films formed via PECVD.

Automated summary

A simple-operation method for designing antireflection coatings (ARCs) based on tailored refractive index characteristics of thin-film materials was developed. High-transmittance, broadband ARCs with specific refractive indices and transmittances were designed and characterized. The sensitivity of the ARCs system to manufacturing errors was simulated. The results provide valuable insights for the preparation of optical films formed via PECVD.