Applications of colloidal crystal patterning for synthesis of 1D and 3D nanostructured semiconductors

We report on two different applications of polystyrene (PS) sphere lithography (colloidal crystal patterning). The first example is related to the classical use of PS spheres as a mask, while in the second example, for the first time, the PS spheres are used as a template to grow semiconductors with complex hierarchical structures. Combining PS nanosphere mask and metal-assisted etching enabled to produce array of well-ordered silicon nanowires (Si-NWs) with uniform diameter. Our contribution in this field was to control the formation of extended arrays of 60 nm diameter Si-NWs on large size Si wafers by downsizing the diameter of the spheres which was nominally 100 nm. The second application is new. By rendering electrically conductive the insulating PS, the spheres were used as a template to grow electrochemically well-ordered ZnO hollow-urchins composed of single-crystal ZnO nanowires (ZnO-NWs). This new nanostructure exhibited dramatically increased light diffusion properties, making it very promising for use in semiconductor-sensitized solar cells.