• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.200-200
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• 2010

In recent times, metal oxide semiconductors thin films transistor (TFT), such as zinc and indium based oxide TFTs, have attracted considerable attention because of their several advantageous electrical and optical properties. There are many deposition methods for fabrication of ZnO-based materials such as chemical vapor deposition, RF/DC sputtering and pulsed laser deposition. However, these vacuum process require expensive equipment and result in high manufacturing costs. Also, the methods is difficult to fabricate various multicomponent oxide semiconductor. Recently, several groups report solution processed metal oxide TFTs for low cost and non vacuum process. In this study, we have newly developed solution-processed TFTs based on Ti-related multi-component transparent oxide, i. e., InTiO as the active layer. We propose new multicomponent oxide, Titanium indium oxide(TiInO), to fabricate the high performance TFT through the sol-gel method. We investigated the influence of relative compositions of Ti on the electrical properties. Indium nitrate hydrate [$In(NO^3).xH_2O$] and Titanium isobutoxide [$C_{16}H_{36}O_4Ti$] were dissolved in acetylacetone. Then monoethanolamine (MEA) and acetic acid ($CH_3COOH$) were added to the solution. The molar concentration of indium was kept as 0.1 mol concentration and the amount of Ti was varied according to weighting percent (0, 5, 10%). The complex solutions become clear and homogeneous after stirring for 24 hours. Heavily boron (p+) doped Si wafer with 100nm thermally grown $SiO_2$ serve as the gate and gate dielectric of the TFT, respectively. TiInO thin films were deposited using the sol-gel solution by the spin-coating method. After coating, the films annealed in a tube furnace at $500^{\circ}C$ for 1hour under oxygen ambient. The 5% Ti-doped InO TFT had a field-effect mobility $1.15cm^2/V{\cdot}S$, a threshold voltage of 4.73 V, an on/off current ratio grater than $10^7$, and a subthreshold slop of 0.49 V/dec. The 10% Ti-doped InO TFT had a field-effect mobility $1.03\;cm^2/V{\cdot}S$, a threshold voltage of 1.87 V, an on/off current ration grater than $10^7$, and a subthreshold slop of 0.67 V/dec.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.379-383
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• 2012

$TiO_2$ thin films consisting of positively charged poly(diallyldimethylammonium chloride)(PDDA) and negatively charged titanium(IV) bis(ammonium lactato) dihydroxide(TALH) were successfully fabricated on glass beads by a layer-by-layer(LBL) self-assembly method. The glass beads used here showed a positive charge in an acid range and negative charge in an alkaline range. The glass beads coated with the coating sequence of(PDDA/TALH)n showed a change in the surface morphology as a function of the number of bilayers. When the number of bilayers(n) of the(PDDA/TALH) thin film was 20, Ti element was observed on the surface of the coated glass beads. The thin films coated onto the glass beads had a main peak of the (101) crystal face and were highly crystallized with XRD diffraction peaks of anatase-type $TiO_2$ according to an XRD analysis. In addition, the $TiO_2$ thin films showed photocatalytic properties such that they could decompose a methyl orange solution under illumination with UV light. As the number of bilayers of the(PDDA/TALH) thin film increased, the photocatalytic property of the $TiO_2$-coated glass beads increased with the increase in the thin film thickness. The surface morphologies and optical properties of glass beads coated with $TiO_2$ thin films with different coating numbers were measured by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD) and by UV-Vis spectrophotometry(UV-vis).

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.440-445
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• 2005

The limitation of measurement accuracy and reliability of autostigmatic null lens system are studied for the cases of using inter-distance of null lenses as the adjustment factor of alignment and fixing the distance by mounting. If we investigate the first case, the wavefront aberration of null lens system is compensated by the adjustment process even though the shape of aspherical surface is not properly fabricated. As the result, it brings about the problem of measurement reliability. However, for the fixing process by mounting null lenses, it doesn't cause the reliability problem because the wavefront aberration of null lens system is not compensated. Further, the fixing process shows nearly same result in measurement accuracy to the adjustment process, that is, $0.0316{\lambda}$ vs. $0.0326{\lambda}$. So, we can conclude the setup for autostigmatic null lens system must be constituted by means of the fixing process. Meanwhile, we introduce and define the alignment aperture on aspheircal mirror, which can be approximated as spherical zone for alignment of null lens system, and besides, we calculate the required fabrication accuracy of the zone for the necessary measurement accuracy.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.446-449
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• 2005

In a directional coupler, the design process requires repeated calculation of the characteristics of every changed structure, because it is generally difficult to expect the extinction ratio to be optimized over the entire variation of design parameters. In this paper, we systematically simulated the extinction ratio as a function of the design parameters, and analyzed the general tendency of that characteristic. In other words, we could find the generalized extinction ratio curve if the separation distance is normalized by the waveguide width. Here, the extinction ratio is shown to be increased as the normalized frequency (v) and the ratio (d) of the separation distance over the waveguide width were increased. For various structures with same ratio d, all corresponding extinction ratio curves as a function of v coincide with each other. We showed the usefulness of the generalized extinction ratio curve by applying it to the design and the fabrication of 1310/l550 nm demultiplexer, as it was convenient to design a shorter directional coupler with targeted extinction ratio from this curve.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.122-127
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• 2021

This paper produces CdS thin film using ITO glass as substrates. The MDS (Multiplex Deposition Sputter System) was used to produce devices by changing RF power and deposition time. The manufactured specimen was analyzed for its optical properties. The purpose of this paper is to find the fabrication conditions that can be applied to the photo-absorbing layer of solar cells. When RF power was 50W and deposition time was 10 minutes, the thickness was measured at 64Å. At 100W, the thickness was measured at 406Å and at 150 W, the thickness was measured at 889Å. Thin films were found to increase in thickness as RF power increased. As a result of the light transmittance measurement, 550-850nm was observed to have a transmittance of approximately 70% or more when the RF power was 50W, 100W, and 150W. Increasing RF power increased thickness and increased particle size, resulting in increased thin film density, resulting in reduced light transmittance. When RF power was 100W and deposition time was 15 minutes, the band gap was calculated at 3.998eV. When deposition time is 20 minutes, it is 3.987eV, 150W is 3.965eV at 15 minutes, and 3.831eV at 20 minutes. It was measured that the band gap decreased as the RF power increased. At XRD analysis, diffraction peaks at 2Θ=26.44 could be observed regardless of changes in RF power and deposition time. The FWHM was shown to decrease with increasing deposition time. And it was measured that the particle size increased as RF power was constant and deposition time was increased.

• Korean Journal of Materials Research
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• v.28 no.12
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• pp.763-768
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• 2018

In this study, glass fibers are fabricated via a continuous spinning process using manganese slag, steel slag, and silica stone. To fabricate the glass fibers, raw materials are put into an alumina crucible, melted at $1550^{\circ}C$ for 2 hrs, and then annealed at $600^{\circ}C$ for 2 hrs. We obtain a black colored glass. We identify the non-crystalline nature of the glass using an XRD(x-ray diffractometer) graph. An adaptable temperature for spinning of the bulk marble glass is characterized using a high temperature viscometer. Spinning is carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of $1109^{\circ}C$ to $1166^{\circ}C$, while the winder speed is in the range of 100rpm to 250rpm. We investigate the various properties of glass fibers. The average diameters of the glass fibers are measured by optical microscope and FE-SEM. The average diameter of the glass fibers is $73{\mu}m$ at 100rpm, $65{\mu}m$ at 150rpm, $55{\mu}m$ at 200rpm, and $45{\mu}m$ at 250rpm. The mechanical properties of the fibers are confirmed using a UTM(Universal materials testing machine). The average tensile strength of the glass fibers is 21MPa at 100rpm, 31MPa at 150rpm, 34MPa at 200rpm, and 45MPa at 250rpm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.382-389
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• 2019

A novel folding process is proposed using a repeated cold-die forging and annealing to form a sterling silver ring. Sterling silver plate was cut into a doughnut shape, and lattices with 0.43-mm line-width were imprinted on it. The sample was folded by forging using dies with slopes of $45^{\circ}$, $60^{\circ}$, and $75^{\circ}$ and annealing. For comparison, samples were also fabricated without annealing. Strain was identified by measuring the length of lattices. Vernier calipers, a Vickers hardness tester, an optical microscope, and a UV-VIS colorimeter were used to determine the size, hardness, microstructure, and body color. Without annealing, cracks occurred. However, successful deformation was possible when annealing was used. The results of macro strain measurements show that the outer diameter and width decreased, while the inner diameter and thickness increased after the final process. The maximum strain was increased 0.128 toward the parallel direction. The Vickers hardness decreased after annealing and increased after the folding process. The microstructure results showed that the grain size increased after annealing but decreased after folding. The color difference based on the Lab index was under 10 for all processes. Eventually, a doughnut-shaped silver plate was successfully deformed into a ring shape by the folding process.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.116-125
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• 2021

A three-dimensional (3D) intraoral scanner, which is one of the major developments in digital dentistry, is widely used in fixed prosthodontics. The application of intraoral scanner is now increasing in removable prosthodontics. Sclerotic change induced by scleroderma causes the limitation of mouth opening and multiple loss of the teeth. Conventional prosthodontic procedures are challenging for patients with this disease. This study showed a case of digital approach to the removable prosthodontic treatment of a patient who had the scleroderma and the consequent microstomia. At the provisional stage, the optical impression of patient's oral structures was digitally obtained. Using a 3D printer, the provisional dentures were fabricated. After extraction of hopeless tooth, the definitive digital impression was taken and the metal frameworks were fabricated, based on the data acquired from the impression. The definitive removable partial dentures were completed and delivered to the patient, who was satisfied with the prostheses.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.1-12
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• 2021

Here, we introduce a laser-induced graphene synthesis technology and its applications for the electric/electronic device manufacturing process. Recently, the micro/nanopatterning technique of graphene has received great attention for the utilization of these new graphene structures, which shows progress developments at present with a variety of uses in electronic devices. Some examples of practical applications suggested a great potential for the tunable graphene synthetic manners through the control of the laser set-up, such as a selection of the wavelength, power adjustment, and optical techniques. This emerging technology has expandability to electric/electronic devices combined together with existed micro-packaging technology and can be integrated with the new processing steps to be applied for the operation in the fields of biosensors, supercapacitors, electrochemical sensors, etc. We believe that the laser-induced graphene technology introduced in this paper can be easily applied to portable small electronic devices and wearable electronics in the near future.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.80-85
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• 2023

New yellow quinoline-dione dye derivatives were designed and synthesized for use in image sensor color filters. The synthesized compounds have a basic chemical structure composed of quinoline and dione groups. New materials were evaluated on the basis of their optical and thermal properties under conditions mimicking those of a commercial device fabrication process. A comparison of their related performances revealed that, between the two prepared compounds, 2-(3-hydroxyquinolin-2(1H)-ylidene)-1H-indene-1,3(2H)-dione (HQIDO) exhibited the superior performance as an image sensor color filter material, including a solubility greater than 0.5 wt% in propylene glycol monomethyl ether acetate solvent and a high decomposition temperature of 298 ℃, respectively. The results suggest that HQIDO can be used as a yellow dye additive in an image sensor colorant.