Figure 4

(a) Original square hole and alternative circular hole grating design; (b) Absorption spectra (calculated by the open-source RCWA software package22) of constrained optimum for proposed fishnet grating structure (blue with circle) and alternative nanodisk structure (red); (c) Fabrication processes of Cr embedded-grating solar absorber using NIL; (d) TEM-SEM image of fabricated Cr embedded-grating solar absorber structure; and (e–g) HAADF-STEM cross-sectional image and EDs elemental mapping image of Cr embedded-grating structures: Cr (red), Si (green), and O (blue).