Ultralow reflection from a-Si nanograss/Si nanofrustum double layers.

Ravipati, Srikanth; Shieh, Jiann; Ko, Fu-Hsiang; Yu, Chen-Chieh; Chen, Hsuen-Li · Adv Mater · 2013

basic_science · Level V

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Abstract

A double-layer nanostructure comprising amorphous Si nanograss on top of Si nanofrustums (NFs) with a total height of 680 nm exhibits ultralow reflection. Almost near-unity absorption and near-zero reflectance result in this layered nanostructure, over a broad range of wavelengths and a wide range of angles of incidence, due to the low packing density of a-Si and the smooth transition of the refractive index from the air to the Si substrate across both the nanograss and NF layers.