ABSTRACT
Technologies capable of fabricating complex shaped silicon metasurfaces attract increasing attention. The focused ion beam fabrication technique is considered traditionally as causing thick damaged layers in silicon resulting in a significant rise of the optical absorption loss. We examine the structure of the FIB-fabricated nanostructures on the silicon-on-sapphire (SOS) platform and its optical characteristics before and after thermal oxidation. We show that being thermally oxidised the FIB-patterned silicon subwavelength nanostructure tends to regain its chiral optical features. The impact of the oxidation process on the silicon nanostructure optical behaviour is discussed.
ABSTRACT
A significant part of the optical metamaterial phenomena has the plasmonic nature and their investigation requires very accurate knowledge of the fabricated structures shape with a focus on the periodical features. We describe a consistent approach to the shape reconstruction of the plasmonic nanostructures. This includes vertical and tilted spike AFM probes fabrication, AFM imaging and specific post-processing. We studied a complex-shaped chiral metamaterial and conclude that the described post-processing routine extends possibilities of the existing deconvolution algorithms in the case of periodical structures with known rotational symmetry, by providing valuable information about periodical features.