Investigation of the porosity and particle size effects on the optical constants of Mn star shape thin films

In this work, Mn star-shaped structures with 3-fold (3 N) and 4-fold symmetries (4 N) were created on glass substrates. The crystallography of the structures was investigated through X-ray diffraction patterns. The surface morphology and cross-section of the samples were examined using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) images, respectively. The optical spectrum of the structures in the wavelength range of 350–1100 nm was obtained using a single beam spectra photometer. By applying reverse homogenization theory and comparing experimental and theoretical results, the porosity percentage and complex refractive index of the structures were determined. The dielectric constant of the structures was also obtained and analyzed using the real and imaginary parts of the complex refractive index. This investigation revealed that structures with higher porosity exhibited larger grains, a higher refractive index, and a larger dielectric constant.