• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.375-386
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• 2022

In the present study, four distinctly colored bacterial isolates that show intense pigmentation upon brief ultraviolet (UV) light exposure are chosen. The strains are identified as Micrococcus luteus (Milky yellow), Cryseobacterium pallidum (Yellow), Cryseobacterium spp. (Golden yellow), and Kocuria turfanensis (Pink) based on their morphological and 16S rDNA analysis. Moderate salinity (1.25%), 25-37℃ temperature, and pH of 7.2 are found to be the most favorable conditions of growth and pigment production for all the selected isolates. The pigments are extracted using methanol: chloroform (1:1) and the purity of the pigments are confirmed by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Further, Fourier transform infrared (FTIR) and UV-Visible spectroscopy indicate their resemblance with carotenoids and flexirubin family. The antioxidant activities of the pigments are estimated, and, all the pigments have shown significant antioxidant efficacy in 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picryl-hydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays. The UV protective property of the pigments is determined by cling-film assay, wherein, at least 25% of UV sensitive Escherichia coli survive with bio-pigments even after 90 seconds of UV exposure compared to control. The pigments also hold a good sun protective factor (SPF) value (1.5-4.9) which is calculated with the Mansur equation. Based on these results, it can be predicted that these bacterial pigments can be further developed into a promising antioxidant and UV-protectant for several biomedical applications.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.87-90
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• 2024

Currently, when oxides are used as insulators in hybrid bonding for 3D integration, they are prone to delamination due to their surface characteristics, and the RC delay value due to the resistance of the metal and the capacitance of the insulator increases as the wiring of the semiconductor chip becomes longer. To solve these problems, we studied the optimization of the conditions of the polymer insulator bonding method for hybrid bonding. To check the possibility of the de-wetting method, we coated a polymer film on the existing micro pillar and conducted hot-press bonding to remove the polymer between the metals. Through this study, it is expected that the introduction of polymers as insulators in hybrid bonding and fine-pitch metal bonding will improve signal transmission speed by reducing RC delay. It is also expected to be commercialized in the future to increase the number of I/O terminals by applying it to hybrid bonding.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.195-195
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• 2016

Titanium and its alloys are widely used as implants in orthopedics, dentistry and cardiology due to their outstanding properties, such as high strength, high level of hemocompatibility and enhanced biocompatibility. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Silicon (Si) and magnesium (Mg) has a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. In vitro studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. The aim of this study is to research Si and Mg doped hydroxyapatite film formation by plasma electrolytic oxidation. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. A Si and Mg coating was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Si and Mg coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.17-21
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• 2007

Dense and periodic arrays of holes and Si nano dots were fabricated on silicon substrate. The nanopatterned holes were approximately $15{\sim}40nm$ wide, 40 nm deep and $40{\sim}80\;nm$ apart. To obtain nano-size patterns, self?assembling diblock copolymer were used to produce layer of hexagonaly ordered parallel cylinders of polymethylmethacrylate (PMMA) in polystyrene(PS) matrix. The PMMA cylinders were degraded and removed with acetic acid rinse to produce a PS. $100\;{\AA}-thick$ Au thin film was deposited by using e-beam evaporator. PS template was removed by lift-off process. Arrays of Au nano dots were transferred by using Fluorine-based reactive ion etching(RE). Au nano dots were removed by sulfuric acid. Si nano dots size and height were $30{\sim}70\;nm$ and $10{\sim}20\;nm$ respectively.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.551-558
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• 2011

This present study was performed to analyze the efficiency and volatility of a porous film containing $Chamaecyparis$ $obtusa$ extract as a method to effectively package food compounds. Phytoncide was contacted the state of gas and showed effective antimicrobial properties. Limonene can be distilled without decomposition as a relatively stable terpene and was one of the extract components. $Chamaecyparis$ $obtusa$ essential oil. The optimal solvent composition was a ratio 5:20:0.3 of T-500:ethanol:hardener to effectively manufacture film containing phytoncide essential oil and the minimum antibacterial concentration was 2%. The films were made under different conditions(A-50LF1, A-25SF2, B-50SF1, C-50LF1, C-25SF2 and D-50SF1) containing phytoncide and the amounts of limonene inside the 1-L reaction chamber depending on storage were measured by gas chromatography-mass selective detention. The results showed that the 25SF2(width, 25 mm; length, 20 cm) revealed more amount of limonene compared with 50LF1(width 50 mm, length 20 cm). We confirmed that the gas emission amount showed a better layer on the film side than on the internal film. An effect of film thickness on phytoncide emissions was observed in that the amounts was less than the expectation for a thicker film at the beginning time, but the emitting amounts increased with increasing storage periods. In the storage testing of various films at $35^{\circ}C$ and 70% humidity for 14 days, 25SF2 showed longer preservation compared with that of 50LF in the case of bread. $C.$ $obtusa$ essential oil is a useful fresh ingredients, hence, analysis of limonene emission kinetics from various film was helpful to develop films with an optimal antimicrobial effect, and will allow application of such films in food packaging systems.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.39-46
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• 2021

The quantitative measurement of interfacial adhesion energy (Gc) of multilayer thin films for Cu interconnects was investigated using a double cantilever beam (DCB) and 4-point bending (4-PB) test. In the case of a sample with Ta diffusion barrier applied, all Gc values measured by the DCB and 4-PB tests were higher than 5 J/㎡, which is the minimum criterion for Cu/low-k integration without delamination. However, in the case of the Ta/Cu sample, measured Gc value of the DCB test was lower than 5 J/㎡. All Gc values measured by the 4-PB test were higher than those of the DCB test. Measured Gc values increase with increasing phase angle, that is, 4-PB test higher than DCB test due to increasing plastic energy dissipation and roughness-related shielding effects, which matches well interfacial fracture mechanics theory. As a result of the 4-PB test, Ta/Cu and Cu/Ta interfaces measured Gc values were higher than 5 J/㎡, suggesting that Ta is considered to be applicable as a diffusion barrier and a capping layer for Cu interconnects. The 4-PB test method is recommended for quantitative adhesion energy measurement of the Cu interconnect interface because the thermal stress due to the difference in coefficient of thermal expansion and the delamination due to chemical mechanical polishing have a large effect of the mixing mode including shear stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.16-19
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• 2019

A thinner film has superior electrical properties and a better amorphous structure. Amorphous structures can be effective in improving conductivity through a depletion effect. Research is needed on the Schottky contact, where potential barriers are formed, as a way to identify these characteristics. $SiO_2/SnO_2$ thin films were prepared to examine the amorphous structure and Schottky contact, $SiO_2$ thin films were prepared using Ar = 20 sccm. $SnO_2$ thin films were deposited using mixed gas with a flow rate of argon and oxygen at 20 sccm, and $SnO_2$ thin films were added by magnetron sputtering and treated at $100^{\circ}C$ and $150^{\circ}C$. To identify the conditions under which the amorphous structure was constructed, the XRD patterns were investigated and C-V and I-V measurements were taken to make Al electrodes and perform electrical analysis. The depletion layer was formed by the recombination of electrons and holes through the heat treatment process. $SiO_2/SnO_2$ thin films confirmed that the pores were well formed when heat treated at $100^{\circ}C$ and an electric current was applied over the micro area. An amorphous $SiO_2/SnO_2$ thin film with heat treatment at $100^{\circ}C$ showed no reflection at $33^{\circ}\;2{\theta}$ in the XRD pattern, and a reflection at $44^{\circ}2\;{\theta}$. The macroscopic view (-30 V

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.729-734
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• 2002

In this study, the polyaniline films of emeraldine base(EB) and lucoemeraldine base(LEB) form chemically doping with poly(sodium-4 styrenesulfonate, PSS) were prepared by casting the mixed solution of chloroform and m-cresol on ITO(indium tin oxide) electrode. By analyzing UV-vis spectra of the mixed solutions, the effects of the secondary doping by m-cresol were obtained. And the conductivity of polyaniline film was increased with increasing m-cresol content. The results suggest that the improvement of conductivity obtained by secondary doping results primarily from interaction of polyaniline and m-cresol. As the results of analyzing cyclic voltammograms, it was known that the redox peak currents of polyaniline electrode prepared from LEB were larger and more reversible than those of polyaniline electrodes prepared from EB. The charge transfer resistances($R_{ct}$) of polyaniline electrodes were reduced with increasing m-cresol content, and LEB/PSS electrodes were smaller than EB/PSS electrodes. This result agrees to the analysis of the redox peak current of cyclic voltammograms. The solution resistance and the capacity of electrical double layer almost unchanged in all prepared polyaniline electrodes. It was confirmed that solution resistance was independent of frequency factor in AC impedance spectra. Also the polyaniline film doping with PSS was revealed pseudo n-type characteristics of conducting polymer.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.289-289
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• 2013

While there are plenty of studies on synthesizing semiconducting germanium nanowires (Ge NWs) by vapor-liquid-solid (VLS) process, it is difficult to inject dopants into them with uniform dopants distribution due to vapor-solid (VS) deposition. In particular, as precursors and dopants such as germane ($GeH_4$), phosphine ($PH_3$) or diborane ($B_2H_6$) incorporate through sidewall of nanowire, it is hard to obtain the structural and electrical uniformity of Ge NWs. Moreover, the drastic tapered structure of Ge NWs is observed when it is synthesized at high temperature over $400^{\circ}C$ because of excessive VS deposition. In 2006, Emanuel Tutuc et al. demonstrated Ge NW pn junction using p-type shell as depleted layer. However, it could not be prevented from undesirable VS deposition and it still kept the tapered structures of Ge NWs as a result. Herein, we adopt $C_2H_2$ gas in order to passivate Ge NWs with carbon sheath, which makes the entire Ge NWs uniform at even higher temperature over $450^{\circ}C$. We can also synthesize non-tapered and uniformly doped Ge NWs, restricting incorporation of excess germanium on the surface. The Ge NWs with carbon sheath are grown via VLS process on a $Si/SiO_2$ substrate coated 2 nm Au film. Thin Au film is thermally evaporated on a $Si/SiO_2$ substrate. The NW is grown flowing $GeH_4$, HCl, $C_2H_2$ and PH3 for n-type, $B_2H_6$ for p-type at a total pressure of 15 Torr and temperatures of $480{\sim}500^{\circ}C$. Scanning electron microscopy (SEM) reveals clear surface of the Ge NWs synthesized at $500^{\circ}C$. Raman spectroscopy peaked at about ~300 $cm^{-1}$ indicates it is comprised of single crystalline germanium in the core of Ge NWs and it is proved to be covered by thin amorphous carbon by two peaks of 1330 $cm^{-1}$ (D-band) and 1590 $cm^{-1}$ (G-band). Furthermore, the electrical performances of Ge NWs doped with boron and phosphorus are measured by field effect transistor (FET) and they shows typical curves of p-type and n-type FET. It is expected to have general potentials for development of logic devices and solar cells using p-type and n-type Ge NWs with carbon sheath.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.317-322
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• 1998

The stabilization of low dielectric constant SiOF films prepared by conventional PECVD using TEOS and $C_2F_6$ was evaluated by the $N_2O$-plasma post-deposition annealing. Properties of SiOF film became unstable when it was air-exposed or heat-treated. Water absorption of SiOF films was increased as F content was increased due to the for¬mation of F -Si- F bonds. Also F content of SiOF films decreased after heat treatment. $N_2O$-plasma post-deposition annealing was proved to be effective on stabilizing SiOF films. which was mainly due to the formation of thin SiON layer near the top surface of films. However. the value of dielectric constant was greatly increased again when $N_2O$-plasma post-deposition annealing was done for a long time. To stabilize the SiOF films without an increase of dielec¬tric constant by $N_2O$- plasma post-deposition annealing. the annealing time should be kept the minimum value. to which stabilizing effects against air environment and heat treatment were preserved.