Fabrication of morphology controllable silicon nanostructure array by chemical etching assisted femtosecond laser near-field modification

Abstract

Periodic silicon nanostructure arrays play crucial role in the fields of the optics, nanophotonics and biotechnology. It’s imperative to fabricate controllable silicon nanostructures with high precision and cost-efficiency. In this study，an elegant approach was proposed for fabricating morphology controllable periodic 3D silicon nanostructure arrays through chemical etching assisted femtosecond laser near-field modification. The employed transparent dielectric microsphere monolayer acted as micro-lens array to confine laser pulse energy in subwavelength region transforming crystalline silicon into amorphous silicon. Based on the etching rate difference between the two phase state in etchant, 3D silicon nanostructure arrays were fabricated. Nanostructures with elliptical and circular shape formed under linearly and circularly polarized laser irradiation and with subsequent wet chemical etching. Various surface nanostructure were prepared including disk-like, ring-like, cone-like and volcano-like nanostructures by tuning laser fluence and chemical etching duration.