For environment-friendly renewable energy, blue energy, which is ocean-related energy, has gained an increasing interest due to its huge potential and vast wasted energy. This study suggests a promising buoy-type ocean energy harvesting structure based on a thermoplastic polymer, poly(methyl methacrylate) (PMMA) as a dielectric film for ocean monitoring system. The PMMA dielectric thin film can be easily fabricated with nanopatterned morphological characteristics by thermal nanoimprinting lithography. The buoy-type suggested energy harvesting structure can convert ocean wave energy into electrical energy to power a commercially available Li-ion battery using a regulator-based circuit.
Plasmonic metasurfaces have been receiving tremendous attention because of their extraordinary optical properties. However, time consuming and expensive fabrication methods such as electron beam lithography or focused ion beam (FIB) hinder its commercial application to sensors, color filters, and photovoltaic solar cells. In this study, we demonstrate that metal-dielectric-metal reflective meta-surfaces can be fabricated in a simple and low-cost way using a one-step covalent bonding-assisted nanotransfer process. We prepared various sizes of nanoscale hole-type patterned silicon master, because the represented color depends on the hole size and period. Ag and SiO2 were deposited onto the replicated polymer stamp from the silicon master, then transferred onto the Al-deposited glass wafer. Strong covalent bonds were formed rapidly between oxygen from the SiO2 and Si from the adhesive. In this way, we easily fabricated metasurfaces using a one-step nanotransfer process. Finally, finite-difference time-domain method (FDTD) simulation was carried out whose outcome matched experimental results, thus verifying our approach.
A bilayer hybrid nanoimprinting (NI) method was developed for fabricating embedded metal nanopatterns with greater processability and improved reliability for enhanced photoluminescence (PL) in optoelectronic devices. Bilayer hybrid NI consists of the following: (a) spin-coating ultraviolet (UV) and thermally curable NI resists in sequence, (b) high-pressure thermal NI and UV exposure while maintaining the stamp in a pressed position, and (c) silver (Ag) deposition and lift-off using a thermal NI resist on the upper surface to create embedded Ag nanoarrays. Reference samples with no Ag nanopatterns and with protruding Ag dot-shaped nanopatterns were also fabricated for comparison. The transmittance and PL of all samples were measured. All samples containing Ag nanopatterns exhibited improved PL compared with reference samples with no Ag. For all pattern sizes, the samples with the embedded Ag nanoarrays exhibited the highest PL; the relative PL enhancements compared with samples with Ag dot-shaped nanoarrays were 32.2%, 36.1%, and 62.7% for pattern sizes of 150, 200, and 265 nm, respectively.
One of the useful applications using NIL is the fabrication of antireflection structure (ARS) which has a sub-wavelength
nanostructure similar to moth-eye below wavelength of visible light because the ARS can be used in anti-glare monitor,
dashboards, and solar cells. The material selection of mold and resin in the NIL process for ARS is very important for
the purpose of real application and mass production. Generally, the mold should have flexibility for continuous mass
production and final structure should have strong durability under outdoor environment. In this work, the effect of single
side and dual side patterning were investigated by change of pitch from moth-eye to photonic crystal on the flexible
polymer substrate by using NIL. Then, the effect of fluorine resin with low refractive index was tested. Finally, a
fabrication method of ARS of pitch of 250nm with high fidelity and accuracy using the high-resolution PDMS mold by
aid of solvent mixing of low viscosity was presented. Generally, it is difficult for Sylgard PDMS to make nanopattern
below 300nm pitch without special treatment.
An etch-less ultraviolet nanoimprint lithography (UV-NIL) process is proposed for patterning a photonic crystal (PC)
structure onto an organic light-emitting diode (OLED) substrate. In a conventional UV-NIL, anisotropic etching is used
to remove the residual layers and to transfer the patterns onto the substrate. The proposed process does not require an
etching process. In the process, a stamp with nano-scale PC patterns is pressed on the dispensed resin and UV light is
then exposed to cure the resin. After tens of seconds, the stamp is separated from the patterned polymer layer on the
substrate. Finally, high-refractive index material is coated onto the layer. The refractive index of the polymer should be
very similar to that of glass. The enhancement of the light extraction was assessed by the three-dimensional (3D) finite
difference time domain (FDTD) method. The OLED was integrated on a nanoimprinted substrate and the electro-luminance
intensity was found to have increased by as much as 50% compared to a conventional device.
We propose a very large-area (> diagonal 20 inch) ultraviolet nanoimprint lithography (UV-NIL) process as a
breakthrough strategy for the thin-film transistor liquid-crystal display (TFT-LCD) industry. The large-area UV-NIL
process is a promising alternative to expensive conventional optical lithography for the production of TFT-LCD panels.
In this study a UV-NIL process using a large area hard stamp in a low vacuum environment is presented. The hard stamp
made from quartz is used for achieving a high overlay accuracy and the vacuum environment is employed to ensure that
air bubble defects are not formed during imprinting. It is demonstrated that the quartz stamp can be used for imprinting
diagonal 20-in. substrates via single-step UV-NIL in a low vacuum environment. Experimental results demonstrate the
potential of the proposed approach as a low-cost lithographic process applicable to flat panel displays.
Two-dimensional (2-D) and three-dimensional (3-D) diamond-like carbon (DLC) stamps for ultraviolet nanoimprint lithography (UV-NIL) were fabricated with two methods: namely, two-photon polymerization (TPP) patterning, followed by nanoscale-thick DLC coating; and a fluorine-doped (F-DLC) coating process, followed by O2 plasma etching. The DLC layer on top of polymer pattern or flat quartz substrate was formed using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process or Direct current (DC) and radio frequency (RF) magnetron sputtering process. It was also demonstrated that the DLC stamp with no anti-adhesion layer could be used for imprinting wafers on UV-NIL and the dimensions of the stamp's features correlated well with the corresponding imprinted features.
Ultraviolet-nanoimprint lithography (UV-NIL) is a promising method for cost-effectively defining nanoscale structures at room temperature and low pressure. To apply a large-area stamp to step-and-repeat UV-NIL in an atmospheric environment for high-throughput, we proposed a new step-and-repeat UV-NIL process using an elementwise patterned stamp (EPS), which consists of elements separated by channels. The proposed UV-NIL is able to imprint an 8-in. wafer with a 5 sq. in EPS in four times. 50 - 80 nm features of the EPS were successfully transferred over 8-in. wafers. The experiments demonstrated that a large-area EPS in the step-and-repeat UV-NIL can be used for imprinting 8-in. wafers in an atmospheric environment.
The hybrid nanocontact printing(HnCP) method is a technology for manufacturing an ultra violet(UV) imprinted silicon substrate from a master and then printing by letting it get in contact with a substrate coated with a metal thin film. It comprises a step in which a master with a nano-pattern is prepared; a step in which the resist is applied to the surface of the silicon substrate; an imprinting step in which the master is let to get in contact with the resist surface, pressurized and then taken off; a step in which the imprinted silicone substrate is manufactured into a nanocontact stamp by curing the resist on the imprinted silicon substrate; a step of inking a self-assembled monolayer on the surface of the imprinted silicone substrate stamp; a step of transferring a printing pattern by letting the imprinted silicone substrate stamp get in contact with the substrate coated with a metal thin film; and a step of forming a desired pattern on the substrate by etching the metal thin film on the substrate to which the printing pattern has been transferred. In case the HnCP method, on which this study is conducted, is used, it enables the stamp manufacturing process to be shortened and optimized, because the nanoocontact printing process is conducted by using an imprinted silicon substrate stamp, and it has the advantage of making the stamp have a large area so that it is possible to produce it in a large quantity through a mass production process. Also, as a hard stamp is used, any error resulting from an ultra micro torsion and mismatching can be prevented in the multi-layering process, and since any deformation or defect is not brought about, the pattern's resolution can be enhanced so that it is possible to embody a pattern of 100nm.
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