Porosity

In porosity characterization option refractive index of the layer is determined as a mixture of a material selected from Layer Material database and Air, Water or Air+Water. You can select how the refractive index of the porous material  is calculated:  average weighted of permittivity, Bruggemann formula or average weighted of refractive indices.

This option is typically used for verification of characterization results.

For example, refractive index of very dense IBS TiO2 film can be considered as  the refractive index of the bulk material (see picture on the right).  If it is assumed that the pores in e-beam evaporated film are filled with water, then the calculated packing of evaporated TiO2 is equal about 85%. 

Find the details in our publications:

  1. T. V. Amotchkina, M.K. Trubetskov, A.V. Tikhonravov, I.B. Angelov, V. Pervak, Reliable optical characterization of e-beam evaporated TiO2 films deposited at different substrate temperatures, Appl. Opt., Vol. 53, Issue 4, pp. A8-A15 (2014)
  2. A. V. Tikhonravov, M. K. Trubetskov, T. V. Amotchkina, A. A. Tikhonravov, D. Ristau, S. Günster, Reliable determination of wavelength dependence of thin film refractive index, Proc. SPIE. 5188, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies 331 (2003).

porosity

 refractive index porous film

thin film porosity Initial and final fittings of experimental transmittance data related to e-beam evaporated TiO2 film (put the mouse on and out of picture)

porous film

 Initial and final fittings of experimental reflectance data related to e-beam evaporated TiO2 film (put the mouse on and out of picture)