Template Synthesis of 3D High-Temperature Silicon-Oxycarbide and Silicon-Carbide Ceramic Photonic Crystals from Interference Lithographically Patterned Organosilicates

The fabrication of 3D diamond-like silicon-oxycarbide and silicon-carbide high-temperature ceramic photonic crystals has been achieved by a strategy involving (1) the use of four-beam interference lithography (IL) to construct a patterned silsesquioxane (POSS) template and (2) infiltration of the polymeric allylhydridopolycarbosilane (AHPCS) silicon-carbide precursor into the patterned PUSS template followed by high temperature ceramic conversion and HF etching. Energy-dispersive X-ray mapping analysis and Fourier transform infrared (FT-IR) studies suggested that the 3D ceramic photonic crystals formed at 1100 degrees C were SiC-like silicon oxycarbide. Additional thermal treatment at 1300 degrees C in vacuo resulted in the carbothermic reduction of the 3D silicon-oxycarbide to form 3D beta-SiC with less than 10% shrinkage in the (111) plane and [111] direction, respectively. The reflectivities of the inverse 3D ceramic photonic crystals obtained at different stages were characterized by FT-I R in the [111] direction. Both the inverse 3D silicon-oxycarbide and silicon-carbide crystals showed bandgaps at 1.84 mu m. These experimental values matched well with the calculated bandgaps, further supporting the robustness of such fabricated 3D ceramic photonic crystals.