Facile nanopatterning of zirconium dioxide films <i>via</i> direct ultraviolet-assisted nanoimprint lithography

다국어 초록 (Multilingual Abstract)

<P>A novel ultraviolet (UV)-assisted imprinting procedure that employs photosensitive zirconyl 2-ethylhexanoate is presented for the fabrication of both amorphous and crystalline zirconium dioxide (ZrO<SUB>2</SUB>) nanostructures. Upon annealing at 400 °C for 1 h, the lateral shrinkage and thickness shrinkage of ZrO<SUB>2</SUB> nanostructures were 69.8 and 66.7%, respectively, indicating an isotropic volume loss. During UV irradiation and annealing treatment, the refractive index of UV-irradiated ZrO<SUB>2</SUB> film is gradually increased by improvement in the packing density and crystallinity of the film. With increasing UV exposure time and annealing temperature, the optical band gap (<I>E</I><SUB>g</SUB>) of the UV-irradiated ZrO<SUB>2</SUB> film is red-shifted from 5.745 to 5.265 eV, due to the removal of organic groups and the resultant densification of the film during the photochemical reaction and the heat-induced increase in the crystallinity of the film. These results suggest that the refractive index and optical <I>E</I><SUB>g</SUB> of ZrO<SUB>2</SUB> nanostructures could be controlled by tuning the conditions of UV exposure time and annealing treatment. Nanopatterns of ZrO<SUB>2</SUB>, fabricated by direct UV-assisted nanoimprint lithography, are potential candidates for protective coatings for optical mirrors and filters, <I>e.g.</I> high-reflectivity mirrors and broadband interference filters, as well as active electro-optical devices where ordered surface nanostructures are necessary.</P> <P>Graphic Abstract</P><P>A novel ultraviolet (UV)-assisted imprinting procedure that employs photosensitive zirconyl 2-ethylhexanoate is presented for the fabrication of both amorphous and crystalline ZrO<SUB>2</SUB> nanostructures. The refractive index and optical band gap of ZrO<SUB>2</SUB> nanostructures could be tuned by varying the UV exposure time and the annealing treatment.
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