A novel and robust route for high-throughput, high-performance nanophotonics-based direct imprint of high refractive index and low visible wavelength absorption materials is presented. Sub-10 nm TiO2 nanostructures are fabricated by low-pressure UV-imprinting of an organic–inorganic resist material. Post-imprint thermal annealing allows optical property tuning over a wide range of values. For instance, a refractive index higher than 2.0 and an extinction coefficient close to zero can be achieved in the visible wavelength range. Furthermore, the imprint resist material permits fabrication of crack-free nanopatterned films over large areas and is compatible for fabricating printable photonic structures.
A novel strategy to pattern optical functional films with high refractive index over large areas is reported. The approach is used to demonstrate for the first time the patterning of sub-10 nm features into inorganic films by nanoimprint lithography. The optical properties of the nanostructured films are easily tuned by post-annealing and their optical transparency is suitable with photonic applications. These results open a promising route for fabricating printable photonic nanodevices with high resolution and high throughput.
Direct ultraviolet imprinting of a functional resist.
SEM pictures of the imprinted TiO2 films showing the shrinkage induced by the annealing process: (a) top-view SEM of the imprinted grating, (b) SEM of the grating after annealing at 400 °C for 10 min; (c) cross-section SEM of a 270 nm linewidth and 700 nm imprinted pitch gratings and (d) SEM of the cross-section after the annealing process at 400 °C for 10 min. The height of the pattern is decreased from 420 nm down to 160 nm after annealing.
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