Fabrication of nanocone arrays by two step metal assisted chemical etching method

This work develops a novel method for preparing a moth eye structure, which has a sub-wavelength periodical Si nanocone structure on Si(100) substrate, using two-step metal assisted chemical etching (MACE). The 1st MACE and 2nd MACE were respectively performed with the intention to form perpendicular Si nanowire arrays on a Si substrate and sharpening the Si nanowire arrays. We found that the inhomogeneous absorption and aggregation of Au particles used as a catalyst for the 2nd MACE was important to obtain the nanocone shape. The obtained Si nanocone arrays showed superior anti-reflecting properties especially in a wavelength below 600 nm compared with the Si nanowire arrays. A possible mechanism involved in the formation of the nanocone structure by the 2 step MACE is discussed in this paper. (C) 2016 Elsevier B.V. All rights reserved.