1D partially oxidized porous silicon photonic crystal reflector for mid-infrared application

A functional structure material with good thermal insulation properties, which can also reflect infrared light within a certain range, was obtained by introducing a photonic crystal structure as a reflector into oxidized porous silicon. The porous silicon multilayer was fabricated based on alternative changes in etching current intensity. The oxidation process was performed to ensure a full oxidation of the high porosity layers and a partial oxidization of the low porosity layers to achieve good thermal insulation properties while maintaining enough contrast of the refractory index. The microstructure was characterized by scanning electron microscopy and the optical reflectance spectra by Fourier transform infrared spectroscopy. A band gap centred at 3 νm with a bandwidth of 1.3 νm was successfully obtained.