Fabrication of highly ordered silicon pin-in-a-hole nanostructures via chemical etching of nanopatterned polymer masks

We present a new technique to fabricate a highly ordered silicon pin-in-a-hole structure, in which each silicon nanowire is pinned in a hole, by combining polymer sphere arrays induced by Rayleigh instability with chemical etching process. With this process, we were able to create the novel structures that are periodic over very large areas (3 x 3 cm(2)), where the length of silicon nanowires can be varied by tuning the etching time. A silicon pin-in-a-hole structure was used as the template for preparing polymer nanotubes. And also these structures exhibited a superior anti-reflection property showing specular reflectance of about 0.2%, nearly three orders of magnitude lower than that of a planar silicon wafer.