One-dimensional alignment of SBA-15 films in microtrenches.

SBA-15 thin films were synthesized by dip-coating in two different types of microtrenches: (a) silicon microtrenches and (b) silicon microtrenches with a deposited low-temperature oxide (LTO) layer. In the upper part of the synthesized films, the pores were aligned along the concave surface in both microtrenches. This alignment was attributed to the capillary force acting during solvent evaporation. In the lower part of the films, the pores were aligned tangentially with the wall in a silicon microtrench whereas they were aligned normal to the wall in a silicon microtrench with a deposited LTO layer. The LTO layer could suppress the growth of mesostructures from the substrate and promote growth from the vapor-liquid interface. The effects of the composition of the precursor solution and relative humidity on pore alignment were also clarified.