Large-scale ordered macroporous SiO2 thin films by a template-directed method

Ordered three-dimensional macroporous SiO2 films were fabricated by colloidal crystal templating. Scanning electron microscope measurements showed that the size of the air sphere replicates that of the initial polystyrene spheres, and that the porous sample exhibits long-range order. Optical measurements show that the macroporous sample exhibits the behavior of a photonic band gap, indicating crystalline order in the sample. Fourier-transform infrared measurements revealed that a strong network of Si-O-Si bonds have been formed throughout the voids of the template before the solidification of the gel. It is proposed that this network hinders the large volume shrinkage during the subsequent heat treatment, and thus high-quality large-scale ordered macroporous films can be obtained. (C) 2002 American Institute of Physics.