Highly Conductive Nanograting–Nanohole Structures with Tunable and Dual-Band Spectral Transparency

Simultaneously increasing electric conductance and optical transmission represents a key challenge for developing a high-quality transparent metallic film (TMF). Using nanosphere lithography and oblique angle deposition, we show that large-area silver nanograting (NG) on nanohole (NH) structures can meet this challenge. The fabricated NG-NH hybrid structure exhibits an excellent sheet resistance as low as 4.53 Omega/sq, an optical transmission of 75.4% from visible to near-infrared, and a high Haacke number up to 13.1, which is superior to that of previously reported metal NH networks or TMFs. Both the electric conductance and optical transparency are anisotropic and can be tuned by the NH diameter, lattice spacing, and the polarization of incident light. In particular, the transparency wavelength bands for different polarized lights are significantly different, which can be used for dual functionalities. The anisotropic electronic property is explained by a two-dimensional resistor network model, and the observed optical responses match well with the results from finite-difference time-domain calculations.