Design optimization and antireflection of silicon nanowire arrays fabricated by Au-assisted chemical etching

Abstract

In this work, we have synthesized a highly periodic silicon nanowire (SiNW) arrays with the spacing from 300 nm to 1000 nm by combining nanosphere lithography (NSL) and metal-assisted chemical etching (MACE). It has been demonstrated that it is effective to produce large-area, well-separated and controlled SiNW arrays. We also present a simple method to solve the problem of distorting spherical shape by angled-deposition method according to shadowing effect during NSL process. So we do not need to reduce the diameter of polystyrene (PS) spheres heavily and avoid making spherical shape distorted and rough. The large-area Au meshes can be further optimized using angled-deposition method and have a small nanohole diameter and relatively large nanohole spacings. And the center-center distance of PSs used as mask merely keeps invariable with 820 nm and 1300 nm pitch after reactive ion etching (RIE) process. The method help improve the distortion of spherical shape heavily during NSL process so that we can obtain SiNW arrays with controlled diameter, length and density using the non-close-packed PSs as the mask. Furthermore, the SiNW arrays obtained by MACE can improve antireflection properties of silicon substrate. The high surface area of SiNW arrays makes the reflectance below 10% or less over a wavelength range of 300–1000 nm. The antireflection structure (ARS) is great of importance in application of nanoscale optical devices.