Vertical deposition of nanospheres on the open sidewalls of silicon pillars

In this paper, we report a simple method, via colloidal suspension evaporation, to deposit monolayer nanospheres vertically onto the open sidewalls of manifold silicon pillar arrays. In experiments we utilize hydrophobic polystyrene (PS) nanospheres and hydrophilic silica nanospheres, and find that the former require more hydrophilic pillar surfaces than the latter do. In addition, proper quantity of nanosphere suspension depends in larger part upon intervals of silicon pillar arrays than upon diameters, and large intervals require more initial nanosphere suspension. More importantly, sidewall angels influence nanosphere distribution significantly and `evaporation angles effect´ should be avoided if homogeneous distribution is expected.