Zeolite films as building blocks for antireflective coatings and vapor responsive Bragg stacks

  by Tsvetanka Babeva, Hussein Awala, Marina Vasileva, Jaâfar El Fallah, Katerina Lazarova, Sebastien Thomas and svetlana mintova

Dalton Trans., 2014, Accepted Manuscript, DOI: 10.1039/C4DT00711E
Received 10 Mar 2014, Accepted 10 Apr 2014

Zeolite films (LTL, BEA and MFI) are prepared with a thickness in the range 50-170 nm through multistep spin-on deposition method. The optical properties of the zeolite films including refractive index, extinction coefficient and thickness are determined from the reflectance spectra using nonlinear curve fitting method. The total free pore volume of the films using the Bruggeman effective medium theory is calculated. The potential of the zeolite films for broadband antireflection (AR) application is demonstrated. Five times reduction of the reflectance of silicon substrate covered with the double AR films comprising of MFI type zeolite (120 nm) deposited on Nb2O5 (60 nm) is achieved. Additionally, the MFI zeolite film is used as a building block of vapor responsive Bragg stacks with a strong response towards acetone. The reversible response of the Bragg stacks towards acetone without additional annealing opens up the possibility to prepare sensors with optical read-out by incorporation of sensitive and transducer elements in a single device.