Study of the optical response of oxidized porous silicon structures by thermal oxidation in air

This work proposes a methodology based on porous silicon (PSi) thermal oxidation in an air atmosphere to reduce its optical losses and change the optical response of one-dimensional photonic structures through the porosity variations, pore filling, and refractive index tuning. First, electrochemical etching was used to fabricate PSi samples at two different anodizing currents and in-situ photoacoustic monitoring was used to guarantee the porous film’s reproducibility. Then, the PSi samples were oxidized in an air atmosphere at temperatures of 600, 800, and 1000 ∘ C and different sintering times (0 h, 5 h, 10 h, and 20 h). All the samples were characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM) to determine the chemical and morphological evolution produced for thermal treatment. In addition, the optical properties were analyzed by UV-Vis spectroscopy before and after the thermal treatment to relate the obtained spectra with the characteristics of the monolayers using the transfer matrix method (TMM), effective medium theory, and genetic algorithms (GA). Finally, we predicted the optical response of oxidized porous silicon one-dimensional photonic crystal for UV-Vis range applications.