Papers by Keyword: Nanopattern

Abstract: A wide range of Light Emitting Diodes (LEDs) applications, from general lighting to transmission sources of the Visual Light Communication (VLC) system, makes the LEDs very important to be developed. This research focuses on comparing LED performance due to the variation in surface size and shape of the LED. The research method is carried out with a simulation and an experimental approach. Before the experiment, the LED was simulated with nanopattern variations to determine the best fabrication parameter. The simulation method is carried out using Ansys Lumerical FDTD 2021. The experiment method used to fabricate nanopatterns on the surface of a semiconductor LED layer uses the nanoimprint lithography method. Stamps for nanoimprint lithography are made using Polydimethylsiloxane (PDMS), and the nanopattern sources are obtained from DVD and Blu-ray grating patterns. The characterization of nanoscale patterns was carried out using a Scanning Electron Microscope (SEM). The light emission intensity is measured using a lux meter at a series of emission angles. The results obtained from this research are that the smaller the width and the periodicity of the grating nanopattern, the light produced will be distributed at a wider angle, but the light intensity will decrease; conversely, for a planar surface without a grating nanopattern, level of focus and intensity of light will be higher. In addition, the thicker the ZnS:Cu layer, the better the intensity of the light produced.

Abstract: Artificial polycarbonate moth eye structured plate was used to emboss the moth eye nano-pattern into PVC films. Embossing was done at 100°C to prevent any damage on polycarbonate template. With embossing of moth eye nano-patterns, transmittance of PVC film was increased up to 6% over 400nm to 800nm wavelength region. This embossed PVC film was then used as an imprint template after depositing thin layer of SiO2 and self-assembled monolayer. Consequently, polymer based moth eye nano-patterns were formed on glass template after UV imprinting and its transmittance was increased from 90% to 92%.

Abstract: Polystyrene-polymethylmethacrylate (PS-PMMA) block copolymers are well known to exhibit microphase separation to form a series of regular structures with local periodic arrangements of the blocks. By developing films of PS-PMMA within topographically patterned silicon (100) substrates (with photolithographically defined rectangular channels of depth 60 nm and widths 166 – 433 nm) these irregular arrangements form highly periodic structures where the features are parallel to the side walls of the channels. However, the use of silicon substrates leads to problems in processing of these films. PS-PMMA does not wet the surface, and this results in island formation on flat substrates. On channel etched substrates this phenomena ensures that the thickness of the films is irregular and poorly defined alignment is seen. Detailed considerations of this polymer system suggest that feature sizes below 25 nm are not realisable. The results suggest other copolymer systems should be studied.

Abstract: The interactions between biological cells and nanometer-scale structured surfaces are very important issues in nanobiotechnology. Most current methods of fabricating such surfaces are costly and are not suitable for the production of a nanometer-scale structured surface that will be used merely as a disposable tool in cell biological studies. We developed and optimized an embossing method of polymers with nanoporous AAOs which is easy, cheap and fast in fabricating nanometer-scale structures on the surface of polymers. We think this method can be applied not only in cellular nanobiotechnogy but also in other areas of nanotechnogy.

Abstract: The surface morphology of the anodic aluminum oxide (AAO) prepared with different surface coating has been studied by AFM and SEM. Under optimized condition, highly ordered stripe patterns have been obtained. These regular patterns, including random stripes and regular stripes, show strong dependence on the crystal orientation of the aluminum substrate. This method can be developed into a novel nanoscale fabrication technique.

Abstract: We have designed and fabricated diamond-shaped AFM cantilevers capable of performing multi-functioning tasks by using single crystal silicon (SCS) micromachining techniques. Structural improvement of the cantilever has clearly solved the crucial problems resulted from using conventional simple beam-AFM cantilever for mechanical testing. After forcecalibration of the cantilever, indentation tests are performed to determine the mechanical behaviors in micro/nano-scale as well as topographic imaging. A diamond Berkovich tip of which radius at the apex is approximately 20 nm is attached on the cantilever for the indentation test and 3D topography measurement. The indentation load-depth curves of nano-scale polymeric pattern (PAK01-UV curable blended resin) are measured and surface topography right after indenting is also obtained. Development of this novel cantilever will extend the AFM functionality into the highly sensitive mechanical testing devices in nano/pico scale.