50 results on '"Kyung Sik Shin"'
Search Results
2. The Sensing of the Crowd through the Screen and the Flux of Changing Affect
- Author
-
Lee Hyeon Seung and Kyung-sik Shin
- Subjects
Environmental science ,Affect (psychology) ,Atmospheric sciences ,Flux (metabolism) ,Social network service - Published
- 2018
- Full Text
- View/download PDF
3. Stimulus-Responsive Contact Lens for IOP Measurement or Temperature-Triggered Drug Release
- Author
-
Jong-Ki Kim, Ji Yoon Kang, Jae-Woo Kim, Kyung-Sik Shin, and Se-Hee Lee
- Subjects
0301 basic medicine ,Intraocular pressure ,medicine.medical_specialty ,Materials science ,genetic structures ,Stimuli responsive ,Contact Lenses ,Biomedical Engineering ,Glaucoma ,Article ,Tonometry, Ocular ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,Ophthalmology ,medicine ,Animals ,Humans ,temperature triggering ,moiré pattern ,Intraocular Pressure ,Temperature ,medicine.disease ,eye diseases ,Contact lens ,Drug Liberation ,030104 developmental biology ,drug delivery ,Drug delivery ,030221 ophthalmology & optometry ,Drug release ,Rabbits ,sense organs ,Drug carrier - Abstract
Purpose Continuous monitoring of elevated intraocular pressure and timely drug delivery for successful treatment of glaucoma are necessary to reduce intraocular pressure (IOP), which shows wide variations across the circadian pattern and in response to medication. This in vivo study presents a new contact lens-based method of optical IOP measurement or temperature-triggered drug elution. Methods A contact lens with moiré patterns of concentric circles measures the changes in eyeball diameter of a rabbit glaucoma model due to changes in IOP by superimposing a camera-captured image onto the micro pattern of the contact lens with a computer-assisted virtual reference image. Drug elution from the nanoporous bicontinuous microemulsion contact lens (BME-CL) into the eye of the rabbit was triggered by a temperature-responsive nanogel drug carrier. Results The moiré pattern change on the contact lens was proportional to the IOP increase in the rabbit eye either ex vivo or in vivo and was also correlated with imaging-based alterations in the anterior chamber angle at a range of IOP values (3–40 mm Hg). The cumulative drug absorbed reached as high as 10.6 µg/mL aqueous humor until 7 days after wearing the BME-CL, and a 33% decrease in IOP was observed at 3 hours after drug elution. Conclusions The results suggest that continuous measurement and treatment of elevated IOP are feasible using moiré pattern-inscribed and thermosensitive drug-eluting contact lenses, respectively. Translational Relevance Pressure-sensing or thermosensitive contact lenses enable monitoring IOP or drug release triggered by body temperature for the treatment of glaucoma patients.
- Published
- 2020
- Full Text
- View/download PDF
4. Nitrogen Radical and Plasma Diagnostics in Dual Frequency Hybrid Plasmas to Investigate N2 /SiH4 PECVD Process
- Author
-
Kyung Sik Shin, Jeon G. Han, Bibhuti Bhusan Sahu, and Masaru Hori
- Subjects
010302 applied physics ,Polymers and Plastics ,Absorption spectroscopy ,Chemistry ,business.industry ,Radical ,Analytical chemistry ,Plasma ,Low frequency ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,symbols.namesake ,Plasma-enhanced chemical vapor deposition ,0103 physical sciences ,symbols ,Optoelectronics ,Langmuir probe ,Capacitively coupled plasma ,Plasma diagnostics ,business - Abstract
The present work addresses a systematic approach for measuring the atomic nitrogen radicals using vacuum ultraviolet absorption spectroscopy (VUVAS) in the N2-SiH4 PECVD processes using alternate plasma concepts. Measurements using VUVAS and RF compensated Langmuir probe reveal that there is significant enhancement in the radical and plasma density when the discharge is operated using the dual frequency hybrid source using the combination of a low and a very high-frequency source. The behavior of low frequency and dual frequency capacitively coupled plasma (CCP) discharges is experimentally investigated. This study also presents a detailed analysis and effectiveness of the dual frequency hybrid plasmas for the practical applications.
- Published
- 2015
- Full Text
- View/download PDF
5. High-performance hybrid cell based on an organic photovoltaic device and a direct current piezoelectric nanogenerator
- Author
-
Keun Young Lee, Zhong Lin Wang, Sang-Woo Kim, Kyung-Sik Shin, Manoj Kumar Gupta, Gyu Cheol Yoon, and Ju-Hyuck Lee
- Subjects
Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Photovoltaic system ,Nanogenerator ,Polymer solar cell ,Hybrid system ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,Hybrid power ,business ,Energy source ,Energy harvesting - Abstract
The search for harvesting both the mechanical and solar energies from a single hybrid system is of significant value and represents a new trend in energy harvesting technologies. This single hybrid system can utilize both the energy sources easily available from nature and most importantly it is clean and sustainable. It is a novel technique involving completely different physical principles utilized for scavenging different types of energies. This report presents studies of a hybrid power generator made a direct-current piezoelectric nanogenerator based on ZnO nanosheets and a bulk heterojunction organic solar cell based on an inverted structure. The device shows much larger electric power output compared to its two individual power output components, which facilitates more effective multi-type energies harvesting and clarifies a mechanism for realizing multi-functional energy devices.
- Published
- 2015
- Full Text
- View/download PDF
6. Effectiveness of plasma diagnostic in ultra high frequency and radio frequency hybrid plasmas for synthesis of silicon nitride film at low temperature.
- Author
-
Sahu, B. B., Kyung Sik Shin, Jin, Su. B., Han, Jeon G., K., Ishikawa, M., and Hori
- Subjects
- *
PLASMA probes , *LANGMUIR probes , *MOLECULAR spectroscopy , *NITRIDES , *SILICON nitride - Abstract
This work presents a systematic plasma diagnostic approach for plasma processing using radio frequency (RF) and RF/UHF (ultra high frequency) hybrid plasmas. The present work also studies the influence of frequency on the deposition of Hydrogenated silicon nitride (SiNx: H) film using N2/SiH4/NH3 discharges. Analysis of data reveals that the UHF power addition to RF is quite effective in the plasma and radicals formation in different operating conditions. For the diagnostics, we have used optical emission spectroscopy, vacuum ultraviolet absorption spectroscopy, and RF compensated Langmuir probe. The presented diagnostic method directly exploits the optimized condition for fabricating high-quality silicon rich nitride (SiNx: H) thin film, at low temperature. With the help of hybrid plasmas, it is possible to fabricate SiNx: H film with high transparency ∼90%. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
7. Growth behaviors and film properties of zinc oxide grown by atmospheric mist chemical vapor deposition
- Author
-
Sang-Woo Kim, Hye-Ji Jeon, Kyung-Sik Shin, Jin-Seong Park, and Seul-Gi Lee
- Subjects
Materials science ,Atmospheric pressure ,Hydrogen ,Mechanical Engineering ,Metals and Alloys ,chemistry.chemical_element ,Chemical vapor deposition ,Zinc ,equipment and supplies ,Active layer ,Solvent ,Chemical engineering ,chemistry ,Mechanics of Materials ,Thin-film transistor ,Environmental chemistry ,Materials Chemistry ,Thin film - Abstract
We evaluated the characteristics of ZnO grown by atmospheric mist chemical vapor deposition at temperatures ranging from 200 °C to 300 °C as a function of the water in the solvent. We also utilized ZnO thin films as an active layer of thin film transistors (TFTs) using the mist CVD process. The mobility measured in the thin-film transistor (TFT) increased with increasing water concentration in the solvent and increasing temperature. We believe that the fact that hydrogen is incorporated in ZnO due to the function of water in the solvent plays an important role in determining the transistor characteristics. The higher deposition temperature functions to increase oxygen vacancies which influences the mobility.
- Published
- 2014
- Full Text
- View/download PDF
8. Piezoelectric coupling in a field-effect transistor with a nanohybrid channel of ZnO nanorods grown vertically on graphene
- Author
-
Sang-Woo Kim, Nae-Eung Lee, Bo-Yeong Kim, Mi Jang, Le Thai Duy, Byeong-Ung Hwang, Vinh Quang Dang, Do-Il Kim, and Kyung-Sik Shin
- Subjects
Materials science ,business.industry ,Graphene ,Transistor ,Nanotechnology ,Electron ,Piezoelectricity ,law.invention ,Nanomaterials ,law ,Modulation ,Optoelectronics ,General Materials Science ,Nanorod ,Field-effect transistor ,business - Abstract
Piezoelectric coupling phenomena in a graphene field-effect transistor (GFET) with a nano-hybrid channel of chemical-vapor-deposited Gr (CVD Gr) and vertically aligned ZnO nanorods (NRs) under mechanical pressurization were investigated. Transfer characteristics of the hybrid channel GFET clearly indicated that the piezoelectric effect of ZnO NRs under static or dynamic pressure modulated the channel conductivity (σ) and caused a positive shift of 0.25% per kPa in the Dirac point. However, the GFET without ZnO NRs showed no change in either σ or the Dirac point. Analysis of the Dirac point shifts indicated transfer of electrons from the CVD Gr to ZnO NRs due to modulation of their interfacial barrier height under pressure. High responsiveness of the hybrid channel device with fast response and recovery times was evident in the time-dependent behavior at a small gate bias. In addition, the hybrid channel FET could be gated by mechanical pressurization only. Therefore, a piezoelectric-coupled hybrid channel GFET can be used as a pressure-sensing device with low power consumption and a fast response time. Hybridization of piezoelectric 1D nanomaterials with a 2D semiconducting channel in FETs enables a new design for future nanodevices.
- Published
- 2014
- Full Text
- View/download PDF
9. Transparent Flexible Graphene Triboelectric Nanogenerators
- Author
-
Kang Hyuck Lee, Seongsu Kim, Hyeon-Jin Shin, Tae Yun Kim, Sang-Woo Kim, Ahrum Sohn, Do Hwan Kim, Kyung Sik Shin, Keun Young Lee, Dong-Wook Kim, Sung Kyun Kim, and Manoj Kumar Gupta
- Subjects
Materials science ,Mechanics of Materials ,Graphene ,law ,Mechanical Engineering ,General Materials Science ,Nanotechnology ,Triboelectric effect ,law.invention - Published
- 2014
- Full Text
- View/download PDF
10. Novel Architecture of Plasmon Excitation Based on Self-Assembled Nanoparticle Arrays for Photovoltaics
- Author
-
Ahrum Sohn, Dong-Wook Kim, Sang-Woo Kim, Kyung Sik Shin, Hanggochnuri Jo, Jae Hyun Kim, and Brijesh Kumar
- Subjects
Materials science ,Organic solar cell ,business.industry ,Nanoparticle ,Nanotechnology ,Surface-enhanced Raman spectroscopy ,Polymer solar cell ,Rhodamine 6G ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,symbols ,Optoelectronics ,General Materials Science ,Surface plasmon resonance ,business ,Raman spectroscopy ,Plasmon - Abstract
An efficient approach to producing hexagonally self-assembled and well-dispersed gold (Au) nanoparticles (NPs) in the pores of porous anodic aluminum oxide (AAO) is reported. This approach is particularly useful for tuning the surface plasmon resonance frequency of Au NPs by varying the effective dielectric constant of AAO. A strongly enhanced Raman spectrum of dye molecule rhodamine 6G using these well-dispersed Au NPs revealed that such a self-assembled Au NP array can induce a strong plasmonic field. Furthermore, we demonstrated a new architecture of plasmon excitation in a bulk heterojunction (BHJ) inverted organic solar cell (IOSC) using the Au NP array with AAO. The optical response of an active layer poly(3-hexylthiophene):(6,6)-phenyl-C61-butyric acid methyl ester was enhanced by this strong plasmonic field associated a well-dispersed Au NP array. A comparative study of AAO with and without Au NPs confirmed plasmonic improvement of the BHJ IOSC. Simulation results showed that Au NPs concentrate the incoming light into a strongly localized field and enhance light absorption in a wide wavelength range.
- Published
- 2014
- Full Text
- View/download PDF
11. Doping Effect of Electron Transport Layer on Nanoscale Phase Separation and Charge Transport in Bulk Heterojunction Solar Cells
- Author
-
Brijesh Kumar, Gyu Cheol Yoon, Kyung-Sik Shin, Hye-Jeong Park, Sang-Woo Kim, and Soon-Wook Jeong
- Subjects
Materials science ,Organic solar cell ,business.industry ,Doping ,Analytical chemistry ,Polymer solar cell ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Active layer ,General Energy ,X-ray photoelectron spectroscopy ,Optoelectronics ,Physical and Theoretical Chemistry ,business ,Short circuit ,Nanoscopic scale ,Layer (electronics) - Abstract
We investigated the influence of the Ga doping in the ZnO interlayer as an electron transport layer (ZnO ETL) on the nanoscale phase separation in the bulk heterjunction (BHJ) layer coated on the ETL as well as the morphological and electrical properties of a low temperature sol−gel-derived pristine ZnO ETL (P-ETL) and Ga-doped ZnO ETL (G-ETL), which affect the performance of inverted organic solar cells (IOSCs). X-ray photoelectron spectroscopy (XPS) confirms the successful incorporation of the element Ga in the ZnO ETL. The short circuit current densities (JSC )o f IOSCs fabricated using a G-ETL were significantly improved from those of IOSCs fabricated with a P-ETL. The maximum JSC was obtained at 2 at. % Ga doping. The IOSCs fabricated with a 2 at. % G-ETL demonstrated power conversion efficiencies of 3.51% (P3HT:PC60BM) and 5.43% (PCDTBT:PC70BM), which were higher than the power conversion efficiencies of 2.88% (P3HT:PC60BM) and 4.90% (PCDTBT:PC70BM) of the IOSCs fabricated with a P-ETL under simulated air mass 1.5 global full-sun illumination. The better performance was attributed to the improved electrical properties of the G-ETL and the enhanced nanoscale phase separation in the BHJ active layer.
- Published
- 2013
- Full Text
- View/download PDF
12. Low temperature synthesis of Al doped ZnO thin films by facing target sputtering
- Author
-
Doo-Hoon Song, Youn-Joun Kim, In Sik Choi, Jeon-Geon Han, Kyung-Sik Shin, and Yoon-Seock Choi
- Subjects
Materials science ,business.industry ,Doping ,Surfaces and Interfaces ,General Chemistry ,Partial pressure ,Sputter deposition ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Sputtering ,Electrical resistivity and conductivity ,Materials Chemistry ,Transmittance ,Optoelectronics ,Thin film ,business ,Power density - Abstract
In this work, aluminum doped zinc oxide (AZO) thin films were synthesized at room temperature on PET substrates by using two different types of magnetron sputtering sources at the same time; deposited from two facing ZnO targets in a confined magnetic field, and co-doped from an Al target located outside of this region. The purpose of this system was not only to retain the advantages of the FTS system but also to propose a new type of doping concept. With this configuration, it was expected to get more flexibility for the tuning of Al concentration by controlling the external doping source. For the first, the gas mixture effect on the film properties was studied. In order to get a high quality crystallographic structure for acquiring high mobility, we controlled Ar working pressure, O 2 partial pressure, and H 2 partial pressure in sequence. After deposition, structural, electrical, optical, and surface morphological characteristics were examined. As a result, we could optimize the gas mixture condition including 2.5 mTorr of Ar, 1.2 sccm of O 2 partial pressure, and 3 sccm of H 2 partial pressure. Secondly, Al doping concentration was controlled by changing the external Al target power density. Moderate carrier concentration could be secured by tuning the Al doping. Also, it was deduced that doping reaction might be increased by the Al particles which had moderate energy. As a result, we could deduce the optimized Al power density as 15 W/cm 2 . Under our optimized condition, AZO films could have good electrical and optical properties with a minimum resistivity of 5.344 × 10 − 4 Ωcm and a maximum transmittance of 90.2%. At the end, TCO performance was derived (13.4 mΩ − 1 ) and this value was found to be valuable compared to other authors' latest works and commercial ITO.
- Published
- 2013
- Full Text
- View/download PDF
13. Design of an auto-focusing actuator with a flexure-based compliant mechanism for mobile imaging devices
- Author
-
Young Pil Park, No-Cheol Park, Choong Kim, Kyung Sik Shin, Youngjun Kim, Kyoung-Su Park, Geum Sik Lee, Jeen Gi Kim, and Myeong Gyu Song
- Subjects
Engineering ,business.industry ,Design of experiments ,Compliant mechanism ,Hinge ,Stiffness ,Voice coil ,Structural engineering ,Condensed Matter Physics ,Finite element method ,Electronic, Optical and Magnetic Materials ,Hardware and Architecture ,medicine ,Electrical and Electronic Engineering ,medicine.symptom ,business ,Actuator - Abstract
There is increasing consumer’s demand for high-quality and high-performance mobile imaging devices. In this paper, an auto-focusing (AF) actuator with a flexure hinge that uses the electromagnetic (EM) circuit of a voice coil motor was designed and evaluated. The flexure hinge was designed by using finite element analysis. The EM circuit was designed based on the structural stiffness of the device. The EM circuit was analyzed using the design of experiments procedure. Based on the results, the effective design parameters were selected, and improvements were made to the design. Finally, a prototype of the AF actuator was manufactured, and the feasibility and performance of the actuator with the flexure hinge were verified experimentally. The experimental results indicated that the proposed actuator performed adequately and satisfied the design requirements.
- Published
- 2013
- Full Text
- View/download PDF
14. ITO-free inverted polymer solar cells using a GZO cathode modified by ZnO
- Author
-
Dukhyun Choi, Woong Choi, Mi-Jin Jin, Xavier Bulliard, Kyung-Sik Shin, Sang-Woo Kim, Yeong Suk Choi, Yungi Kim, Jong Hwan Park, Min Kim, Tae Sang Kim, Jae-Young Choi, Sungyoung Yun, Soo-Ghang Ihn, Myungsun Sim, and Kilwon Cho
- Subjects
Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Inorganic chemistry ,Energy conversion efficiency ,Polymer solar cell ,Cathode ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Photoactive layer ,law ,Solar cell ,Optoelectronics ,Thin film ,business ,Layer (electronics) - Abstract
A gallium-doped ZnO (GZO) layer was investigated and compared with a conventional indium-tinoxide (ITO) layer for use as a cathode in an inverted polymer solar cell based on poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) bulk heterojunctions (BHJ). By modifying the GZO cathode with a ZnO thin layer, a high power conversion efficiency (3.4%) comparable to that of an inverted solar cell employing the same P3HT:PCBM BHJ photoactive layer with a conventional ITO/ZnO cathode was achieved. This result indicates that GZO is a transparent electrode material that can potentially be used to replace high-cost ITO.
- Published
- 2011
- Full Text
- View/download PDF
15. Selective growth of ZnO nanorods on SiO2/Si substrates using a graphene buffer layer
- Author
-
Jae-Young Choi, Hyeon-Jin Shin, Dukhyun Choi, Seon-Mi Yoon, Hyo Sug Lee, Ki-Hong Kim, Won Mook Choi, Sang-Woo Kim, and Kyung-Sik Shin
- Subjects
Materials science ,business.industry ,Graphene ,Nanotechnology ,Heterojunction ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Buffer (optical fiber) ,law.invention ,law ,Optoelectronics ,General Materials Science ,Nanorod ,Electrical and Electronic Engineering ,business ,Layer (electronics) ,Solution process - Abstract
A promising strategy for the selective growth of ZnO nanorods on SiO2/Si substrates using a graphene buffer layer in a low temperature solution process is described. High densities of ZnO nanorods were grown over a large area and most ZnO nanorods were vertically well-aligned on graphene. Furthermore, selective growth of ZnO nanorods on graphene was realized by applying a simple mechanical treatment, since ZnO nanorods formed on graphene are mechanically stable on an atomic level. These results were confirmed by first principles calculations which showed that the ZnO-graphene binding has a low destabilization energy. In addition, it was found that ZnO nanorods grown on SiO2/Si with a graphene buffer layer have better optical properties than ZnO nanorods grown on bare SiO2/Si. The nanostructured ZnO-graphene materials have promising applications in future flexible electronic and optical devices.
- Published
- 2011
- Full Text
- View/download PDF
16. Nano-crystalline silicon thin films grown by the inductively coupled plasma assisted CFUBM at low temperature
- Author
-
Yuichi Setsuhara, Jeon G. Han, Yoon S. Choi, Kyung Sik Shin, and In S. Choi
- Subjects
Argon ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Sputter deposition ,Condensed Matter Physics ,Grain size ,Surfaces, Coatings and Films ,symbols.namesake ,chemistry ,Cavity magnetron ,Materials Chemistry ,symbols ,Crystallite ,Thin film ,Inductively coupled plasma ,Raman spectroscopy - Abstract
The hydrogenated nano-crystalline silicon thin films were deposited on glass substrates at low temperatures in an argon and hydrogen atmosphere using inductively coupled plasma (ICP) — assisted closed field unbalanced magnetron sputtering (CFUBM) system. A one-turn ICP coil was installed to dissociate the hydrogen molecules by the induced magnetic field inside the chamber. The emission intensity, I Hα (656.28 nm), was saturated at a magnetron RF (13.56 MHz) power of 400 W and increased with increasing ICP RF (13.56 MHz) power. The Raman peak of the silicon thin film shifted from 480 cm − 1 (amorphous phase) to 520 cm − 1 (crystalline phase) with increasing ICP power. The crystalline volume fraction of the silicon thin films was 65% at an ICP power of 400 W and the crystallite grain size was approximately 7 nm. X-ray diffraction and Fourier-transform infrared spectroscopy were used to examine the structural changes and chemical bonding state, respectively.
- Published
- 2010
- Full Text
- View/download PDF
17. Inverted Organic Solar Cells with ZnO Thin Films Prepared by Sol–Gel Method
- Author
-
Brijesh Kumar, Hye-Jeong Park, Kyung-Sik Shin, Soon-Wook Jeong, Kang Hyuck Lee, and Sang-Woo Kim
- Subjects
Spin coating ,Organic solar cell ,Chemistry ,Inorganic chemistry ,Substrate (electronics) ,Hybrid solar cell ,Electronic, Optical and Magnetic Materials ,law.invention ,Chemical engineering ,law ,Solar cell ,Electrical and Electronic Engineering ,Thin film ,Layer (electronics) ,Sol-gel - Abstract
The influences of buffer layers on the performance of hybrid solar cells that are fabricated with an active layer blend of poly (3-hexylthiophene) (P3HT) and [6, 6]-phenyl-C61-buytyric acid methyl ester (PCBM), were investigated. The ZnO thin films were used as an electron transport layer in solar cells to improve the photovoltaic performances. To explore the effects of ZnO film thickness, ZnO thin films were deposited as an electron transport layer by spin coating them one to four times at 4000 rpm using zinc acetate dehydrate that was dissolved in a mixed solution of 2-methoxyethanol and ethanolamine. We fabricated IOSCs on PES substrate, consist of Au/MoO 3 /PCBM:P3HT/ZnO/ITO. The optical property of the ZnO buffer layers was investigated. Furthermore, we found the optimum ZnO buffer layer by using the sol―gel method to enhance the performance of the solar cells.
- Published
- 2010
- Full Text
- View/download PDF
18. Mist-CVD Growth of High Quality ZnO Thin Films at Low Temperature for Inverted Organic Solar Cells
- Author
-
Kwon-Ho Kim, Brijesh Kumar, Kyung-Sik Shin, Sang-Woo Kim, and Kyung-Kook Kim
- Subjects
Organic solar cell ,Scanning electron microscope ,Chemistry ,business.industry ,Chemical vapor deposition ,Substrate (electronics) ,Tin oxide ,Electronic, Optical and Magnetic Materials ,Field emission microscopy ,Crystallinity ,Optics ,Chemical engineering ,Electrical and Electronic Engineering ,Thin film ,business - Abstract
We report the deposition of ZnO thin films on indium-doped tin oxide (ITO)-coated glass substrates via Mist chemical vapor deposition (Mist-CVD) at a temperature range of 250, 300 and 350 °C, respectively. Surface morphology and crystalline quality were investigated by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD), respectively and optical property by transmission spectra. Further, we have optimized the surface morphology of ZnO films for inverted organic solar cells (IOSCs) by fabricating IOSCs on glass substrate, consisting of Au/MoO 3 /PCBM:P3HT/ZnO/ITO. It was found that the photovoltaic power conversion efficiency (PCE) of IOSCs is affected by the transmittance and crystallinity of ZnO thin films.
- Published
- 2010
- Full Text
- View/download PDF
19. Morphology Control of ZnO Nanorods on ITO Substrates in Solution Processes
- Author
-
Sam-Dong Lee, Sang-Woo Lee, Sang-Woo Kim, Kyung-Sik Shin, and Soon-Wook Jeong
- Subjects
Spin coating ,Materials science ,Aqueous solution ,Oxide ,chemistry.chemical_element ,Nanoparticle ,Nanotechnology ,Zinc ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Nanorod ,Layer (electronics) ,Solution process - Abstract
We report growth of vertically well-aligned zinc oxide (ZnO) nanorods on indium-tin oxide (ITO)/glass substrates using a simple aqueous solution method at low temperature via control of the ZnO seed layer morphology. ZnO nanoparticles acting as seeds are pre-coated on ITO-coated glass substrates. by spin coating to control distribution and density of the ZnO seed nanoparticles. ZnO nanorods were synthesized on the seed-coated substrates in a dipping process into a main growth solution. It was found that the alignment of ZnO nanorods can be effectively manipulated by the spin-coating speed of the seed layer. A grazing incidence X-ray diffraction pattern shows that the ZnO seed layer prepared using the higher spin-coating speed is of uniform seed distribution and a flat surface, resulting in the vertical growth of ZnO nanorods aligned toward the [0001] direction in the main growth process.
- Published
- 2009
- Full Text
- View/download PDF
20. Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope
- Author
-
Jae Yeol Lee, Jeen Gi Kim, Junghoon Lee, Do Sun Nam, Jong Se Park, Byung-youn Song, and Kyung Sik Shin
- Subjects
Engineering ,business.product_category ,Pixel ,business.industry ,Electrical engineering ,Voice coil ,Condensed Matter Physics ,Handset ,Electronic, Optical and Magnetic Materials ,law.invention ,Optical axis ,Hardware and Architecture ,law ,Electrical and Electronic Engineering ,business ,Actuator ,Diaphragm (optics) ,Digital camera ,Camera module - Abstract
Recent cellular phones have high-resolution, compact digital camera modules that have several millions of pixels. Although being small, such several mega-pixel camera modules definitely need to be able to execute auto-focusing and/or optical zooming in order to obtain precise images. Hence, image photographing devices having driving mechanisms that can move a lens group in the direction parallel to an optical axis have appeared such as piezoelectric type, linier motor type, and voice coil motor type. Although these technologies are already popular in existing digital cameras, driving mechanism for camera modules in cellular phones needs to be extremely improved because their requirements are totally different from usual digital cameras. Compact image photographing devices, which are installed in mobile apparatuses, should improve portability by reducing their sizes and weights and increase use-time of a battery by reducing power consumption. Weakened suspension (e.g. thickness is 0.02 mm or less) in order to minimize an elastic coefficient for drastic decrease of driving current frequently occurs permanent step-out of a lens group by plastic deformation of the metal suspensions when it comes to getting shocks from accidental drops of a handset. The proposed auto-focusing actuator using conductive polyimide as a flexible diaphragm satisfies these requirements of ultra slim cell phones. This polyimide suspension shows ultimate toughness when it comes to drop-test of cell phones. This actuator also shows high performance quite enough for several mega-pixel camera modules for ultra slim cellular phones; the moving range is up to 0.35 mm, the DC sensitivity is 0.2 mm/140 mA, and the resistance at the terminal is 22 Ohm, whereas the aperture is 6.8 mm, and the overall size is 10 × 10 × 3.95 mm. Most of all, the robustness against drop and shock has been dramatically increased, with no change of reliability under high temperature and high humidity condition, because of the flexibility of the conductive polyimide suspension.
- Published
- 2009
- Full Text
- View/download PDF
21. Growth of ZnO Nanostructures on Various Substrates by Simple Aqueous Solution Method
- Author
-
Mi-Jin Jin, Soon-Wook Jeong, Sang-Woo Kim, Sam-Dong Lee, and Kyung-Sik Shin
- Subjects
Crystal ,Crystallinity ,Materials science ,Nanostructure ,Aqueous solution ,Chemical engineering ,Sapphire ,Nanotechnology ,Nanorod ,Substrate (electronics) ,Epitaxy - Abstract
Growth of well-aligned ZnO nanostructures on various substrates such as GaN, ITO/glass, and sapphire was realized via a simple aqueous solution method at low temperature of . Morphology of ZnO nanostructures grown on various substrates as function of substrate was studied. It was found that ZnO nanostructures is a strong function of substrate. It was clearly observed that the morphology of ZnO nanostructures could be varied by change of substrate. Morphology, crystallinity, and crystal characteristics were carried out by FE-SEM, synchrotron x-ray scattering measurements, and high-resolution electron microscopy, respectively.
- Published
- 2008
- Full Text
- View/download PDF
22. Structure and mechanical properties of ZrCrAlN nanostructured thin films by closed-field unbalanced magnetron sputtering
- Author
-
Ho Y. Lee, Kyung Sik Shin, Youn J. Kim, W.S. Jung, Jeon G. Han, and Yong M. Kim
- Subjects
Materials science ,Mineralogy ,Surfaces and Interfaces ,General Chemistry ,Partial pressure ,Sputter deposition ,Condensed Matter Physics ,Microstructure ,Grain size ,Surfaces, Coatings and Films ,Sputtering ,Physical vapor deposition ,Cavity magnetron ,Materials Chemistry ,Composite material ,Thin film - Abstract
Quaternary ZrCrAlN nanostructured thin films were synthesized by Closed-Field Unbalanced Magnetron Sputtering, and their microstructure and mechanical properties of the ZrCrAlN nanostructured thin films were examined. The grain refinement of the ZrCrAlN nanostructured thin films was controlled by adjusting the N2 partial pressure. The hardness of the film varied with the N2 partial pressure and the maximum value was approximately 45 GPa. It was also confirmed that there is a critical value of the grain size, dc, needed to maximize the hardness.
- Published
- 2007
- Full Text
- View/download PDF
23. Ferroelectric Polarization in CH3NH3PbI3 Perovskite
- Author
-
Sung Kyun Kim, Manoj Kumar Gupta, Nam-Gyu Park, Hyun Suk Jung, Kyung-Sik Shin, Byeong Jo Kim, Hui-Seon Kim, and Sang-Woo Kim
- Subjects
Materials science ,Condensed matter physics ,business.industry ,Poling ,Ferroelectricity ,Crystal ,Polarization density ,Piezoresponse force microscopy ,Optics ,Electric field ,General Materials Science ,Physical and Theoretical Chemistry ,Polarization (electrochemistry) ,business ,Perovskite (structure) - Abstract
We report on ferroelectric polarization behavior in CH3NH3PbI3 perovskite in the dark and under illumination. Perovskite crystals with three different sizes of 700, 400, and 100 nm were prepared for piezoresponse force microscopy (PFM) measurements. PFM results confirmed the formation of spontaneous polarization in CH3NH3PbI3 in the absence of electric field, where the size dependency to polarization was not significant. Whereas the photoinduced stimulation was not significant without an external electric field, the stimulated polarization by poling was further enhanced under illumination. The retention of ferroelectric polarization was also observed after removal of the electric field, in which larger crystals showed longer retention behavior compared to the smaller sized one. Additionally, we suggest the effect of perovskite crystal size (morphology) on charge collection at the interface of the ferroelectric material even though insignificant size dependency in electric polarization was observed.
- Published
- 2015
24. Issue of particle formation in the high rate film deposition by plasma assisted deposition processes
- Author
-
Bibhuti Bhusan Sahu, Su B. Jin, J. S. Lee, Jeon G. Han, and Kyung Sik Shin
- Subjects
Materials science ,Sputtering ,Etching (microfabrication) ,Plasma-enhanced chemical vapor deposition ,Particle ,Deposition (phase transition) ,Nanotechnology ,Plasma ,Plasma processing ,Charged particle - Abstract
Particle contamination in processing plasma reactors that are designed for deposition, etching, and sputtering applications e.g., for solar cells, flat panel displays, and chip production often plays a crucial role in the quality and the yield of the processed products. Although plasma enhanced chemical vapour deposition (PECVD) is presently still the workhorse of the semiconductor industry, it is also suffers from the drawback of dust production, which is linked to the use of plasma. For instance the formation of dust, caused by the positive potential in the bulk of the plasma, which traps negatively charged particles, is a serious issue. The reduction or removal of such particles poses a major technological challenge for plasma-assisted processing, which needs to be addressed.
- Published
- 2015
- Full Text
- View/download PDF
25. Nanopatterned textile-based wearable triboelectric nanogenerator
- Author
-
Tae Yun Kim, Sang-Hyun Kim, Kyung Sik Shin, Jung Ho Kim, Wanchul Seung, Ju-Hyuck Lee, Sang-Woo Kim, Manoj Kumar Gupta, Jianjian Lin, and Keun Young Lee
- Subjects
Textile ,Materials science ,Silver ,General Physics and Astronomy ,Nanotechnology ,chemistry.chemical_compound ,Electric Power Supplies ,Electricity ,General Materials Science ,Dimethylpolysiloxanes ,Triboelectric effect ,Mechanical Phenomena ,Nanotubes ,Polydimethylsiloxane ,business.industry ,Textiles ,General Engineering ,Nanogenerator ,High voltage ,chemistry ,Optoelectronics ,Nanorod ,Zinc Oxide ,business ,Voltage - Abstract
Here we report a fully flexible, foldable nanopatterned wearable triboelectric nanogenerator (WTNG) with high power-generating performance and mechanical robustness. Both a silver (Ag)-coated textile and polydimethylsiloxane (PDMS) nanopatterns based on ZnO nanorod arrays on a Ag-coated textile template were used as active triboelectric materials. A high output voltage and current of about 120 V and 65 μA, respectively, were observed from a nanopatterned PDMS-based WTNG, while an output voltage and current of 30 V and 20 μA were obtained by the non-nanopatterned flat PDMS-based WTNG under the same compressive force of 10 kgf. Furthermore, very high voltage and current outputs with an average value of 170 V and 120 μA, respectively, were obtained from a four-layer-stacked WTNG under the same compressive force. Notably it was found there are no significant differences in the output voltages measured from the multilayer-stacked WTNG over 12 000 cycles, confirming the excellent mechanical durability of WTNGs. Finally, we successfully demonstrated the self-powered operation of light-emitting diodes, a liquid crystal display, and a keyless vehicle entry system only with the output power of our WTNG without any help of external power sources.
- Published
- 2015
26. Gating effect of suspended multiwalled carbon nanotube with all-shell rooted from electrodes: parallel growth from ferromagnetic catalytic contact
- Author
-
Byeong Kwon Ju, Chang Hoon Choi, Yoon Teak Jang, Kyung Sik Shin, Yun-Hi Lee, Chang Woo Lee, and Dong Ho Kim
- Subjects
Nanotube ,Nanoelectromechanical systems ,Materials science ,business.industry ,General Physics and Astronomy ,Nanotechnology ,Carbon nanotube ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Carbon nanotube field-effect transistor ,law.invention ,Condensed Matter::Materials Science ,Nanoelectronics ,Ferromagnetism ,law ,Electrode ,Optoelectronics ,Field-effect transistor ,Physical and Theoretical Chemistry ,business - Abstract
We describe the gate coupling of a rooted grown suspended carbon nanotube (CNT) between two microsized catalytic contact electrodes using a direct parallel growth technique. All-shell Multiwalled carbon nanotubes (MWNTs) were bonded to contact electrodes because MWNTs were grown from the electrodes. The response characteristics of the devices with the gate voltage show typical p-type field effect transistor function at a high-temperature regime and asymmetric Coulomb blockage behavior in low temperatures. Results of the observation suggest that our unique structure, i.e., catalytic ferromagnetic electrode/all-shell bonded MWNT/ferromagnetic electrode, made by direct parallel growth may be a promising key element for nanoelectronics and nanoelectro-mechanical-systems (NEMS).
- Published
- 2004
- Full Text
- View/download PDF
27. Synthesis of functional ZnO nanowall networks using simple solution etching
- Author
-
Min-Su Yi, Sang Yeol Lee, Sang-Woo Kim, Kyung-Sik Shin, and Brijesh Kumar
- Subjects
Photoluminescence ,Materials science ,Exciton ,Biomedical Engineering ,Nanowire ,Analytical chemistry ,Bioengineering ,Heterojunction ,General Chemistry ,Chemical vapor deposition ,Conductivity ,Condensed Matter Physics ,Impurity ,Etching (microfabrication) ,General Materials Science - Abstract
We report the synthesis of high quality single crystalline ZnO nanowall networks (NNs) using ammonia solution etching of a ZnO nanowire-nanowall heterojunction (NNH) structure. Synchrotron X-ray diffraction revealed that the full-width-at-half-maximum of the ZnO (0002) peak in the ZnO NN sample was much narrower than that of the ZnO NNH sample. Temperature-dependent photoluminescence (PL) measurements revealed more intense and narrower bound exciton peak emission in the NN sample compared to that in the NNH sample. Moreover, the clear observation of free exciton emission in the PL spectrum of the NN sample, even at temperatures as low as 30 K, suggested incorporation of a small number of impurities into the NN sample. In addition, I-V characteristics confirm the higher conductivity of the ZnO NNs as compared to those of the NNH structures, indicating that the NN sample had a superior crystalline property than NNH sample.
- Published
- 2014
28. Hydrophobic sponge structure-based triboelectric nanogenerator
- Author
-
Ju-Young Kim, Myung Hwa Kim, Sang-Woo Kim, Jeong Min Baik, Keun Young Lee, Na Ri Kang, Jinsung Chun, Ju-Hyuck Lee, Manoj Kumar Gupta, Kyung Sik Shin, and Kyeong Nam Kim
- Subjects
Record value ,Materials science ,Mechanical Engineering ,Static Electricity ,Nanogenerator ,Electric Conductivity ,Sustainable energy ,Electric Power Supplies ,Mechanics of Materials ,Structure based ,Nanotechnology ,General Materials Science ,Dimethylpolysiloxanes ,Composite material ,Current density ,Energy harvesting ,Hydrophobic and Hydrophilic Interactions ,Triboelectric effect ,Voltage ,Aluminum ,Mechanical Phenomena - Abstract
Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated. The output voltage and current density reach a record value of 130 V and 0.10 mA cm(-2) , respectively, giving over 10-fold power enhancement, compared with the flat film-based triboelectric nanogenerator.
- Published
- 2014
29. High deposition rate microcrystalline silicon films prepared by magnetic mirror assisted RF-PECVD
- Author
-
Yoon S. Choi, In S. Choi, Sung H. Cho, Kyung Sik Shin, Jeon G. Han, and Youn J. Kim
- Subjects
Diffraction ,Materials science ,Analytical chemistry ,General Physics and Astronomy ,Plasma ,Silane ,Magnetic mirror ,symbols.namesake ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Plasma-enhanced chemical vapor deposition ,symbols ,General Materials Science ,Thin film ,Raman spectroscopy - Abstract
Intrinsic hydrogenated microcrystalline silicon (mu c-Si:H) thin films were deposited on glass substrates with a different silane concentration (SC = 100 x SiH(4)/(SiH(4) + H(2))). A magnetic mirror was applied geometrically in the RF (13.56 MHz) plasma enhanced chemical vapor deposition (PECVD) system to increase the deposition rate. The deposition rate using the confined magnetic field (0.72 nm/s with high crystalline volume fraction of 76.6% at SC of 3.5%) was approximately 7 times higher than that using conventional RF-PECVD. High resolution X-ray diffraction and Raman spectroscopy were used to examine the structure of the mu c-Si:H thin films, the plasma properties were analyzed by optical emission spectrum (OES). The main reasons for the improved deposition rate and crystallinity of the mu c-Si:H thin films are discussed. Crown Copyright (C) 2010 Published by Elsevier B. V. All rights reserved.
- Published
- 2010
- Full Text
- View/download PDF
30. Ferroelectric coupling effect on the energy-band structure of hybrid heterojunctions with self-organized P(VDF-TrFE) nanomatrices
- Author
-
Sang-Woo Kim, Hyeok Kim, Kyung-Sik Shin, Sung Kyun Kim, Wanchul Seung, Sungjin Kim, Tae Yun Kim, SeongMin Kim, Manoj Kumar Gupta, and Gyu Cheol Yoon
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Photovoltaic system ,Heterojunction ,Ferroelectricity ,Coupling (electronics) ,Photoactive layer ,Coupling effect ,Mechanics of Materials ,Optoelectronics ,General Materials Science ,Composite material ,Polarization (electrochemistry) ,business ,Electronic band structure - Abstract
Ferroelectric coupling effects on the energy-band structure of hybrid heterojunctions are investigated using hybrid photovoltaic devices with poly(3-hexylthiophene-2,5-diyl) (P3HT)/ZnO and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). The self-organized P(VDF-TrFE):P3HT photoactive layer forms a novel architecture consisting of P3HT domains in a P(VDF-TrFE) matrix. The energy-band structure at the interface of the p-n heterojunction is tuned by artificial control of the ferroelectric polarization of the P(VDF-TrFE) material, consequently modulating the photovoltaic performance of the hybrid photovoltaic devices.
- Published
- 2014
31. Enhancement of light extraction efficiency of GaN-based light-emitting diodes by ZnO nanorods with different sizes
- Author
-
Sangbin Lee, Semi Oh, Kyoung-Kook Kim, Sang-Woo Kim, Hyeongwoo Yu, Soohaeng Cho, and Kyung-Sik Shin
- Subjects
Materials science ,Surface Properties ,Biomedical Engineering ,Bioengineering ,Gallium ,Rod ,law.invention ,law ,Materials Testing ,General Materials Science ,Particle Size ,Lighting ,Hexagonal crystal system ,business.industry ,Extraction (chemistry) ,General Chemistry ,Equipment Design ,Condensed Matter Physics ,Nanostructures ,Equipment Failure Analysis ,Energy Transfer ,Semiconductors ,Optoelectronics ,Nanorod ,Zinc Oxide ,business ,Voltage ,Light-emitting diode - Abstract
The improvement of the optical output power of GaN-based light emitting diodes (LEDs) was achieved by employing nano-sized flat-top hexagonal ZnO rods. ZnO nanorods (NRs) with the average diameters of 250, 350, and 580 nm were grown on p-GaN top surfaces by a simple wet-chemical method at relatively low temperature (90 degrees C) to investigate the effect of the diameter of ZnO NRs on the light extraction efficiency. Consequently, the enhancement by the factor of as high as 2.63 in the light output intensity at 20 mA for the LED with 350 nm ZnO NRs was demonstrated without the increase in the operation voltage compared to the reference LED.
- Published
- 2013
32. Coulomb blockade devices of Co dot arrays on tungsten-nanowire templates fabricated by using only a thin film technique
- Author
-
Dong Ho Kim, Yoon Taek Jang, Yun Hi Lee, Kyung Sik Shin, Chang Hoon Choi, and Byeong Kwon Ju
- Subjects
Fabrication ,Materials science ,Physics and Astronomy (miscellaneous) ,Nanowire ,chemistry.chemical_element ,Coulomb blockade ,Nanotechnology ,Tungsten ,law.invention ,chemistry ,Quantum dot ,law ,Nanodot ,Thin film ,Photolithography - Abstract
A simple fabrication of gate-controlled nanodevices made of the Co nanodots on tungsten (W)-nanowire templates by using conventional photolithography and a thin film technique is reported. The combined multiple grain nanobridge allows the observation of the Coulomb gap up to a temperature as high as 200 K and shows nonlinear current–voltage characteristics up to 250 K. The combination of Co dots with straight W-nanowire templates opens possibilities of reproducible blockade devices.
- Published
- 2003
- Full Text
- View/download PDF
33. Inverted organic solar cells with ZnO nanowalls prepared using wet chemical etching in a KOH solution
- Author
-
Sang-Hyeob Kim, Kyung-Sik Shin, Kwon-Ho Kim, Brijesh Kumar, Sang-Woo Kim, and Hye-Jeong Park
- Subjects
Aqueous solution ,Materials science ,Organic solar cell ,business.industry ,Inorganic chemistry ,Photovoltaic system ,Energy conversion efficiency ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Substrate (electronics) ,Condensed Matter Physics ,Isotropic etching ,Optoelectronics ,General Materials Science ,Thin film ,business ,Short circuit - Abstract
We report on the photovoltaic (PV) performances of inverted organic solar cells (IOSCs) that were fabricated from PCBM:P3HT polymer with a ZnO thin film and ZnO nanowalls as electron transport and hole block layers. ZnO thin film on ITO/glass substrate was deposited using a simply aqueous solution route. ZnO nanowall structures were obtained via wet chemical etching of ZnO thin films in a KOH solution. The power conversion efficiency (PCE) of the IOSC with ZnO nanowalls was significantly improved by 44% from 1.254% to 1.811% compared to that of the IOSC with ZnO thin film. The short circuit current in IOSCs fabricated with the ZnO nanowalls was increased mainly due to the increase in the charge transport interface area, as a result of enhancement in the PCE. This work suggests a method for fabricating efficient PV devices with a larger charge transport area for future prospects.
- Published
- 2012
34. Low-temperature solution-based growth of ZnO nanorods and thin films on Si substrates
- Author
-
Dae-Woo Jeon, Do Kyung Lee, Mi-Jin Jin, Sang-Woo Kim, Kyung Sik Shin, Sam Dong Lee, In Hwan Lee, Dae Ho Yoon, and Soon Wook Jeong
- Subjects
Photoluminescence ,Aqueous solution ,Materials science ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Crystal structure ,Condensed Matter Physics ,Lattice mismatch ,Blueshift ,Emission band ,Chemical engineering ,General Materials Science ,Nanorod ,Thin film - Abstract
ZnO nanorods and thin films were synthesized on Si(100) substrates at a low temperature by controlling the ZnO seed formation in an aqueous solution process. Vertically well-aligned ZnO nanorods with a single-crystalline hexagonal structure and c-axis growth orientation were obtained despite having a different crystal structure than a large lattice mismatch with the Si(100) substrate. In addition, the authors suggest that the lateral growth of ZnO nanorods causes them to merge together into ZnO thin films during growth into the aqueous solution. It is also suggested that the significant blueshift of the main emission band in the photoluminescence spectrum obtained from the nanorod sample at 10 K can be mainly attributed to Burstein-Moss effects in the ZnO nanorods.
- Published
- 2009
35. Integrated approach for low-temperature synthesis of high-quality silicon nitride films in PECVD using RF–UHF hybrid plasmas
- Author
-
Bibhuti Bhusan Sahu, Kyung Sik Shin, and Jeon G. Han
- Subjects
010302 applied physics ,Materials science ,Silicon ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Plasma ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Silicon nitride ,Plasma-enhanced chemical vapor deposition ,0103 physical sciences ,symbols ,Langmuir probe ,Electron temperature ,Plasma diagnostics ,0210 nano-technology ,Nitriding - Abstract
This study investigates low-temperature plasma nitriding of hydrogenated silicon (SiN x :H) film in radio frequency (RF) and RF–ultra-high frequency (UHF) hybrid plasmas. To study the optimized conditions for the deposition of SiN x :H film, this work adopts a systematic plasma diagnostic approach in the nitrogen–silane and nitrogen–silane–ammonia plasmas. This work also evaluates the capability of plasma and radical formation by utilizing different plasma sources in the PECVD process. For the plasma diagnostics, we have purposefully used the combination of optical emission spectroscopy (OES), intensified CCD (ICCD) camera, vacuum ultraviolet absorption spectroscopy (VUVAS), and RF compensated Langmuir probe (LP). Data reveal that there is significant enhancement in the atomic nitrogen radicals, plasma densities, and film properties using the hybrid plasmas. Measurements show that addition of a small amount of NH3 can significantly reduce the electron temperature, plasma, and radical density. Also, optical and chemical properties of the deposited films are investigated on the basis of plasma diagnostics. Good quality SiN x :H films, with atomic nitrogen to hydrogen ratio of 4:1, are fabricated. The plasma chemistry of the hybrid plasmas is also discussed for its utility for plasma applications.
- Published
- 2016
- Full Text
- View/download PDF
36. The serial dilution chip for cytotoxicity and cell differentiation test
- Author
-
Choong Kim, Kangsun Lee, Sung Shin Ryu, Kyung Sik Shin, Tae Song Kim, Ji Yoon Kang, and Kyu Jung Lee
- Subjects
Materials science ,Serial dilution ,Diffusion ,Pipette ,Linear scale ,Analytical chemistry ,Chip ,Standard deviation ,Dilution ,Volumetric flow rate - Abstract
This paper proposes two types of serial dilution devices for linear and logarithmic concentration gradient. The designs of serial dilution chips were based on the adjustment of flow rate to obtain desired dilution ratio, so that they are not affected by molecular size, flow rate, and diffusion length. The performance of linear dilution chip was verified by image analysis of diluted tryphane blue solution as well as by cytotoxicity test. The analysis of the color intensity indicated that the tryphane blue solution was diluted in linear scale, which was in good agreement with the theoretical value. The percentage of viable cells linearly increased with the concentration of PFA and the standard deviation was within 0.05%. Also, the experiment of logarithmic dilution chip demonstrated that the concentrations of outlet was logarithmically linear, regardless of the variation of flow rates and was in accordance with that of dilution by manual pipetting.
- Published
- 2007
- Full Text
- View/download PDF
37. Tailoring of microstructure in hydrogenated nanocrystalline Si thin films by ICP-assisted RF magnetron sputtering
- Author
-
Manish Kumar, Jeon G. Han, Kyung Sik Shin, Komgrit Leksakul, and Bibhuti Bhusan Sahu
- Subjects
Materials science ,Acoustics and Ultrasonics ,business.industry ,Analytical chemistry ,Substrate (electronics) ,Sputter deposition ,Condensed Matter Physics ,Microstructure ,Nanocrystalline material ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Crystallinity ,Cavity magnetron ,Optoelectronics ,Inductively coupled plasma ,Thin film ,business - Abstract
Utilizing plasma-assisted deposition by combining an RF magnetron and an inductively coupled plasma (ICP) source it is possible to fabricate highly crystallized nc-Si:H films at a relatively low substrate temperature (300 °C). Microstructural analysis reveals enhancement in crystallinity along with (2 2 0) preferential orientation throughout the depth of the film. The possible mechanism of crystallinity enhancement and preferential orientation is presented on the basis of plasma diagnostics using optical emission spectroscopy and various film analysis tools. This work also reports the effectiveness of the ICP source and elevated temperature for the control of film microstructure and crystallinity.
- Published
- 2015
- Full Text
- View/download PDF
38. Utility of dual frequency hybrid source for plasma and radical generation in plasma enhanced chemical vapor deposition process
- Author
-
Jeon G. Han, Masaru Hori, Bibhuti Bhusan Sahu, and Kyung Sik Shin
- Subjects
Physics and Astronomy (miscellaneous) ,Absorption spectroscopy ,Chemistry ,Radical ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,Plasma ,Nanocrystalline material ,symbols.namesake ,Plasma-enhanced chemical vapor deposition ,symbols ,Langmuir probe ,Radio frequency ,Plasma processing - Abstract
Looking into the aspect of material processing, this work evaluates alternative plasma concepts in SiH4/H2 plasmas to investigate the radical and plasma generation in the plasma enhanced chemical vapor deposition (PECVD) synthesis of nanocrystalline Si (nc-Si:H). Simultaneous measurements by vacuum ultraviolet absorption spectroscopy (VUVAS), optical emission spectroscopy (OES), and radio frequency (RF) compensated Langmuir probe (LP) reveal that RF/ultrahigh frequency (UHF) hybrid source can efficiently produce H radicals and plasmas that are accountable for nc-Si:H film synthesis. The efficacy of hybrid plasmas is also discussed.
- Published
- 2015
- Full Text
- View/download PDF
39. Effectiveness of hydrogen dilution for designing amorphous to crystalline Si thin film in inductively coupled plasma assisted magnetron sputtering
- Author
-
Jeon G. Han, Masaru Hori, Bibhuti Bhusan Sahu, and Kyung Sik Shin
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,General Engineering ,Nanocrystalline silicon ,Analytical chemistry ,General Physics and Astronomy ,Plasma diagnostics ,Plasma ,Sputter deposition ,Thin film ,Inductively coupled plasma ,Microstructure ,Amorphous solid - Abstract
Careful analysis and investigations of the formation mechanism of the microstructure of the hydrogenated nanocrystalline silicon (nc-Si:H) film is presented. A systematic approach is made to understand the transition from amorphous (a-Si:H) to crystalline (nc-Si:H) by incorporating hydrogen dilution using inductively coupled plasma (ICP) assisted magnetron sputtering. Film analysis and plasma diagnostics results reveal that one can design desired microstructure simply by controlling H2 dilution and energy control in the plasmas.
- Published
- 2015
- Full Text
- View/download PDF
40. Plasma diagnostic approach for high rate nanocrystalline Si synthesis in RF/UHF hybrid plasmas using a PECVD process
- Author
-
Kenji Ishikawa, Kyung Sik Shin, Jeon G. Han, Bibhuti Bhusan Sahu, Yudai Miyawaki, and Masaru Hori
- Subjects
Surface coating ,symbols.namesake ,Materials science ,Plasma-enhanced chemical vapor deposition ,Nanocrystalline silicon ,Analytical chemistry ,symbols ,Langmuir probe ,Plasma diagnostics ,Plasma ,Chemical vapor deposition ,Condensed Matter Physics ,Plasma processing - Abstract
Hydrogenated nanocrystalline silicon (nc-Si : H) films intended for efficient nc-Si : H solar cells are usually made at the transition to the nanocrystalline regime using the plasma-enhanced chemical vapor deposition (PECVD) process. This change occurs within a sensitive process window and is affected by various deposition parameters. This paper reports a study of nc-Si : H films' fabrication by utilizing systematic plasma diagnostics. This work presents a novel approach for plasma processing using radio frequency (RF), ultra high frequency (UHF) and RF/UHF hybrid plasmas. Using careful analysis, efforts are made to investigate the radicals and plasma formation by changing the operating source power and silane (SiH4) concentration. The aim of this work is also to investigate the PECVD process and conditions favorable for the synthesis of nc-Si : H film. For the present study, we systematically use the optical emission spectroscopy (OES), normal, and RF-compensated Langmuir probe (LP) and vacuum ultraviolet absorption spectroscopy diagnostics. Measurements reveal that the OES diagnostic is consistent with the LP measurements. Investigation reveals that UHF power in addition to RF enables higher dissociation of H or SiH radicals and the production of higher plasma density. The combined effect of both RF and UHF sources is used as the hybrid plasma source. Measurements also reveal that inbetween SiH4 flow rates ~20–30 sccm, there is significant change in the plasma characteristics that denotes the nc-Si : H−a-Si : H transition region. An atomic hydrogen density (nH) in the range ≈(8 − 10) × 1011 cm−3 and plasma density n0 ≈ (2 − 3) × 1011 cm−3 with a silane to hydrogen ratio of 1–2% with high crystallinity has been obtained. Along with the discussion on the effect of frequency on plasma chemistry, this explains the RF power coupling and the role of electrons and ions in plasmas with increasing frequency.
- Published
- 2015
- Full Text
- View/download PDF
41. Nanogenerators: Hydrophobic Sponge Structure-Based Triboelectric Nanogenerator (Adv. Mater. 29/2014)
- Author
-
Myung Hwa Kim, Kyeong Nam Kim, Ju-Hyuck Lee, Jeong Min Baik, Jinsung Chun, Keun Young Lee, Na-Ri Kang, Ju-Young Kim, Kyung-Sik Shin, Manoj Kumar Gupta, and Sang-Woo Kim
- Subjects
Materials science ,Mechanics of Materials ,Mechanical Engineering ,Nanogenerator ,Structure based ,General Materials Science ,Nanotechnology ,Triboelectric effect - Published
- 2014
- Full Text
- View/download PDF
42. Nanogenerators: Transparent Flexible Graphene Triboelectric Nanogenerators (Adv. Mater. 23/2014)
- Author
-
Seongsu Kim, Ahrum Sohn, Do Hwan Kim, Hyeon-Jin Shin, Tae Yun Kim, Keun Young Lee, Manoj Kumar Gupta, Kang Hyuck Lee, Dong-Wook Kim, Sang-Woo Kim, Kyung-Sik Shin, and Sung Kyun Kim
- Subjects
Materials science ,Mechanics of Materials ,Graphene ,law ,Mechanical Engineering ,General Materials Science ,Nanotechnology ,Energy harvesting ,Triboelectric effect ,law.invention - Published
- 2014
- Full Text
- View/download PDF
43. Reliable operation of a nanogenerator under ultraviolet light via engineering piezoelectric potential
- Author
-
Thanh Toan Pham, Sang-Woo Kim, Brijesh Kumar, Ju-Hyuck Lee, Manoj Kumar Gupta, Kwon-Ho Kim, Keun Young Lee, and Kyung-Sik Shin
- Subjects
Materials science ,Passivation ,Renewable Energy, Sustainability and the Environment ,business.industry ,Screening effect ,Nanogenerator ,Nanotechnology ,medicine.disease_cause ,Pollution ,Piezoelectricity ,Nuclear Energy and Engineering ,Ultraviolet light ,medicine ,Environmental Chemistry ,Optoelectronics ,Microelectronics ,Nanorod ,business ,Ultraviolet - Abstract
It is essential to stabilize and enhance the power output performance of piezoelectric nanogenerators (NGs) in order to use them as a sustainable power source for wireless sensors, microelectronics, and optoelectronic devices. Here, we report a facile route to stabilize and maximize the output performance of a zinc oxide (ZnO) nanorod (NR)-based NG in the presence of ultraviolet (UV) light by reducing the piezoelectric potential screening effect caused by the free electrons in the ZnO NRs via surface passivation. We experimentally and theoretically investigated the piezoelectric potential drop in the ZnO NR-based NG due to the piezoelectric potential screening effect. A simple thermal annealing treatment was applied to the pristine ZnO NRs in air atmosphere to stabilize the output performance of the NG even in the presence of UV light. The piezoelectric output voltage from the surface-passivated NG was approximately 25 times higher than that from the NG with no passivation under UV light illumination.
- Published
- 2013
- Full Text
- View/download PDF
44. High quality graphene-semiconducting oxide heterostructure for inverted organic photovoltaics
- Author
-
Hanggochnuri Jo, Won Mook Choi, Hyeon-Jin Shin, Kyung-Sik Shin, Jae-Young Choi, and Sang-Woo Kim
- Subjects
Materials science ,Organic solar cell ,business.industry ,Graphene ,Energy conversion efficiency ,Nanotechnology ,Heterojunction ,General Chemistry ,Substrate (electronics) ,Polymer solar cell ,law.invention ,Sputtering ,law ,Materials Chemistry ,Optoelectronics ,Thin film ,business - Abstract
In this work, we demonstrate damage-free direct growth of high-quality semiconducting ZnO thin films on thermal chemical vapor deposition (CVD)-grown graphene transferred onto a plastic substrate. A mist pyrolysis CVD (MPCVD) method based on a non-vacuum process at a low growth temperature of 160 °C is introduced for the successful direct growth of ZnO on graphene without any additional treatments or processes. ZnO thin films that did not exhibit damage to the structural and electrical properties of graphene were successfully grown on graphene. The MPCVD-grown ZnO thin films revealed more uniform surface morphology and better structural property than ZnO thin films deposited using sol–gel and sputtering. Using the ZnO/graphene heterostructure, we fabricated bulk heterojunction inverted organic photovoltaics with a power conversion efficiency of 1.55%.
- Published
- 2012
- Full Text
- View/download PDF
45. Low-temperature growth and characterization of ZnO thin films for flexible inverted organic solar cells
- Author
-
Brijesh Kumar, Kyung-Sik Shin, Soo-Ghang Ihn, Hye-Jeong Park, Kyoung-Kook Kim, and Sang-Woo Kim
- Subjects
Materials science ,Organic solar cell ,business.industry ,Energy conversion efficiency ,chemistry.chemical_element ,General Chemistry ,Chemical vapor deposition ,Substrate (electronics) ,chemistry ,Materials Chemistry ,Optoelectronics ,Thin film ,business ,Tin ,Layer (electronics) ,Indium - Abstract
Flexible inverted organic solar cells (IOSCs) with a zinc oxide (ZnO) thin film layer acting as an effective electron transport layer and a low reflective light absorber were fabricated in this study. The high quality ZnO thin films on flexible indium tin oxide-coated polyethersulfone (PES) substrates were grown in a non-vacuum process using mist pyrolysis chemical vapor deposition at a low temperature of 180 °C without any thermal damage to the PES substrate. The power conversion efficiency of the flexible IOSCs with ZnO thin films averaged 3.1% at a simulated air-mass of 1.5 global full-sun (100 mW cm−2) illumination, which was greater than that of flexible IOSCs with a ZnO thin film formed using a sol–gel method (approximately 2.3%).
- Published
- 2011
- Full Text
- View/download PDF
46. An Examination of Banner Communication in the US Military as Compared to the Korean Army.
- Author
-
Jang-song Lee and Kyung-sik Shin
- Subjects
MILITARY communications ,BANNERS ,ARMED Forces - Abstract
A military banner is designed to present many pieces of information on the unit that it represents. It should basically indicate the name of the unit, its size (or echelon), and its function including its branch. It also shows the tradition of the unit and the values and aims the unit cherishes. These things are represented by means of various signs including shapes, figures, colors, icons, linguistic expressions, etc. The purpose of this study is to examine what and how a military banner communicates to its viewers. From the point of view of communication, it is to specify how a message is decoded by a receiver. Among many theories proposed to explicate the relation between the signifier of a sign and what it signifies, this study adopts Peircean Theory of Semiotics as the frame of reference. More specifically, it examines the banners of the ROK Army and the US Army to investigate the linking mechanism of a signifier (or representamen in Peircean terminology) to its signifier (or object in Percean sense), subcategorizing the mechanism into (1) linking by convention, (2) chains established by severed links, and (3) linking by metaphor. [ABSTRACT FROM AUTHOR]
- Published
- 2009
47. The actuator for high-speed CD/DVD rewritable system.
- Author
-
Byung Youn Song, Dae Jong Jang, Do Sun Narn, Kyung Sik Shin, Pyong Yong Seong, and Jo Hyung Lee
- Published
- 2002
- Full Text
- View/download PDF
48. Tailoring of microstructure in hydrogenated nanocrystalline Si thin films by ICP-assisted RF magnetron sputtering.
- Author
-
Kyung Sik Shin, Bibhuti Bhusan Sahu, Manish Kumar, Komgrit Leksakul, and Jeon Geon Han
- Subjects
SILICON films ,THIN film research ,NANOCRYSTALS ,INDUCTIVELY coupled plasma spectrometry ,MAGNETRON sputtering - Abstract
Utilizing plasma-assisted deposition by combining an RF magnetron and an inductively coupled plasma (ICP) source it is possible to fabricate highly crystallized nc-Si:H films at a relatively low substrate temperature (300 °C). Microstructural analysis reveals enhancement in crystallinity along with (2 2 0) preferential orientation throughout the depth of the film. The possible mechanism of crystallinity enhancement and preferential orientation is presented on the basis of plasma diagnostics using optical emission spectroscopy and various film analysis tools. This work also reports the effectiveness of the ICP source and elevated temperature for the control of film microstructure and crystallinity. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
49. Utility of dual frequency hybrid source for plasma and radical generation in plasma enhanced chemical vapor deposition process.
- Author
-
Kyung Sik Shin, Bibhuti Bhusan Sahu, Jeon Geon Han, and Masaru Hori
- Abstract
Looking into the aspect of material processing, this work evaluates alternative plasma concepts in SiH
4 /H2 plasmas to investigate the radical and plasma generation in the plasma enhanced chemical vapor deposition (PECVD) synthesis of nanocrystalline Si (nc-Si:H). Simultaneous measurements by vacuum ultraviolet absorption spectroscopy (VUVAS), optical emission spectroscopy (OES), and radio frequency (RF) compensated Langmuir probe (LP) reveal that RF/ultrahigh frequency (UHF) hybrid source can efficiently produce H radicals and plasmas that are accountable for nc-Si:H film synthesis. The efficacy of hybrid plasmas is also discussed. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
50. Effectiveness of hydrogen dilution for designing amorphous to crystalline Si thin film in inductively coupled plasma assisted magnetron sputtering.
- Author
-
Kyung Sik Shin, Bibhuti Bhusan Sahu, Jeon Geon Han, and Masaru Hori
- Abstract
Careful analysis and investigations of the formation mechanism of the microstructure of the hydrogenated nanocrystalline silicon (nc-Si:H) film is presented. A systematic approach is made to understand the transition from amorphous (a-Si:H) to crystalline (nc-Si:H) by incorporating hydrogen dilution using inductively coupled plasma (ICP) assisted magnetron sputtering. Film analysis and plasma diagnostics results reveal that one can design desired microstructure simply by controlling H
2 dilution and energy control in the plasmas. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.