Impact of thermal oxidation on the structural and optical properties of porous silicon microcavity

We report the structural and optical characterization of one-dimensional porous silicon microcavities. These structures are based on a planar resonator formed by two high-reflectance mirrors separated by a thin active optical spacer. In order to simulate and predict the optical properties of the microcavity, the transfer matrix method is used. A strong correlation between the formation parameters and the reflectance spectra is introduced. The prepared microcavities are exposed to thermal oxidation. The resonance position of the microcavity exhibits a blueshift proportional to the degree of oxidation. Structural changes of the microcavities after oxidation are investigated and analyzed using X-ray diffraction and Raman spectroscopy. The observed shift of characteristic silicon peak is attributed to the reduction of silicon crystallites as the oxidation increases.