Searching
for the relationship between the nanostructure and optical
properties has always been exciting the researchers in the field of
optics (linear optics as well as non-linear optics), energy harvesting
(anti-reflective Si solar cells, perovskite solar cells, ..., etc.),
and industry (anti-reflection coating on car windows, sunglasses,
etc.). In this work, we present an approach for nanostructuring the
silicon substrate to silicon photonic crystals. By precisely controlling
the etching time and etching path after using nanoimprint lithography,
ordered arrays of inverted Si nanopyramids and Si nanopillars with
good homogeneity, uniform surface roughness, high reproducibility
of pattern transfer, and a controllable aspect ratio are prepared.
Experimental investigation of the optical properties indicates that
the reflections of these Si nanostructures are mainly determined by
the aspect ratio as well as the period of nanostructures. Furthermore,
we have experimentally observed visible-light scattering (V-LS) patterns
on inverted Si nanopyramids and Si nanopillars, and their corresponding
patterns can be precisely controlled by the patterned nanostructures.
The V-LS pattern, background, and “ghost peaks” on the
angle-resolved scattering results are caused by constructive interference,
destructive interference, and the interference situation between both.
This controllable nanopatterning on crystalline Si substrates with
precisely tunable optical properties shows great potential for applications
in many fields, for example, optics, electronics, and energy.