• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1051-1054
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• 2009

This paper investigates approaches for improving effective mobility of organic thin film transistors (OTFTs). We consider gate dielectric optimization, whereby we demonstrated >2x increase in mobility by using a silicon-rich silicon nitride ($SiN_x$) gate dielectric for polythiophene-based (PQT) OTFTs. We also engineer the dielectric-semiconductor ($SiN_x$-PQT) interface to attain a 27x increase in mobility (up to 0.22 $cm^2$/V-s) using an optimized combination of oxygen plasma and OTS SAM treatments. Augmentative material systems by combining 1-D nanomaterials (e.g., carbon nanotubes, zinc oxide nanowires) in an organic matrix for nanocomposite OTFTs provided a further boost in device performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.343-344
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• 2007

Carrier mobility was measured using time-of-flight (TOF) measurements to investigate the transport properties of holes and electrons in stabilized a-Se film. A laser beam with pulse duration of 5 ns and wavelength of 350 nm was illuminated on the surface of a-Se with thickness of $400\;{\mu}m$. The measured transit times of hole and electron were about $8.73\;{\mu}s\;and\;229.17\;{\mu}s$, respectively. The experimental results showed that the hole and electron drifting mobility were $0.04584\;cm^2V^{-1}S^{-1}\;and\;0.00174\;cm^2V^{-1}s^{-1}\;at\;10\;V/{\mu}m$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.15-19
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• 2007

This paper reports the effects of Ar ion beam surface treatment on a $SiO_2$ dielectric layer in organic thin film transistors. We compared the electrical properties of pentacene-based OTFTs, treated by $O_2$ plasma or Ar ion beam treatments and characterized the states of the surface of the dielectric by using atomic force microscopy and X-ray photoelectron spectroscopy. For the sample which received $O_2$ plasma treatment, the mobility increased significantly but the on/off current ratio was found very low. The Ar ion beam-treated sample showed a very high on/off current ratio as well as a moderately improved mobility. XPS data taken from the dielectric surfaces after each of treatments exhibit that the ratio of between Si-O bonds and O-Si-O bonds was much higher in the $O_2$ plasma treated surface than in the Ar ion beam treated surface. We believe that our surface treatment using an inert gas, Ar, carried out an effective surface cleaning while keeping surface damage very low, and also the improved device performances was achieved as a consequence of improved surface condition.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.7-23
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• 1990

The success or failure of endosseous dental implants is related to the cellular activity at the implant surface. Success seems to be associated with the enclosure of the implant in a non-inflammed connective tissue or the formation of a direct bone implant interface. The purpose of this study was to examine the tissue reactions to the various implants at the submergible state in dog mandible. The $Br\"{a}nemark$, Core-Vent, Intergral, Bone spiral were selected for evaluation and also the Kimplant, Nephrite were used for the experimental study. After 4 months the animals were sacrificed. The interface zone between bone and implant was investigated using x-rays, light microscope, scanning electron microscope, transmission electron microscope. The following results were obtained from this study. 1. $Br\"{a}nemark$, Core-Vent, Kimplant, Integral showed no mobility and bone growth over the healing screws of the implants. Histologically most of the implant surface were covered by remodelled lamellar bone, and partly by a cellular layer or the thin fibrous tissue layer. 2. The Bone spiral showed no mobility and partially radiolucent line around the implant. The upper part of the implant was surrounded by a thin fibrous connective tissue and the middle, apical part of it were contacted with bone directly. 3. The Nephrite implant showed severe mobility and a radiolucent line around the implant. Histologically it showed mild inflammation and was surrounded by a fibrous connective tissue. 4. Scanning electron microscope showed that there was no amorphous ground substance in the Nephrite implant but the formation of ground substance over the collagen filaments in other implants. 5. Transmission electron microscope showed that collagen filaments were approached irregularly to the surface of all implants and in the $Br\"{a}nemark$, Core-Vent, Kimplant, Integral there was amorphous layer between the implant and the collagen filaments. It seemed to be ground substances.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.12
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• pp.46-53
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• 1997

The TMA gas sensors are fabricated with the ZnO-based thin films grown by a RF magnetron sputtering method. The hall effect measurement and AES analysis are carried out to investigate the effects of the sputtering gases and dopants which effect on the electrical resistivity and sensitivity to TMA gas. We measure the cfhanges of the surface carrier concentration, haall electron mobility, electrical resistivity, surface condition, and depth profile of the films. The ZnO-based thin film sensors sputtered in oxygen, or added with dopants showed a high sruface carrier concentration, film sensors sputtered in oxygen and doped with 4.0 wt.% $Al_{2}$O$_{3}$, 1.0 wt.% TiO$_{2}$, and 0.2 wt% v$_{2}$O$_{5}$ showed the highest surface carrier concentration of 5.952 * 10$^{20}$ cm$^{-3}$ , hall electron mobility of 176.7 cm$^{2}$/V.s, lowest electrical resistivity of 6*10$^{-5}$ .ohm.cm and highest sensitivity of 12. These results were measured at a working temperature of 300.deg. C to 8 ppm TMA gas.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.667-670
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• 2009

The understanding of behaviors of hydroperoxyl/superoxide anion radicals (${H_2O_2}^./{O_2}^{-.}$) generated from a photoirradiated $TiO_2$ surface is essential to improve the efficiency of $TiO_2$ photocatalytic reactions by decreasing the recombination of photoinduced electron-hole ($e^--h^+$) pairs. In contrast with previous studies, we found that ${H_2O_2}^./{O_2}^{-.}$ generated on the surface of illuminated $TiO_2$ particles are mobile. ${H_2O_2}^./{O_2}^{-.}$ formed by the photocatalysis of $TiO_2$ particles immobilized onto the inner surface of a coil-quartz tube were forced under a continuous flow through a knotted tubing reactor (KTR) and into the aqueous phase completely separated from the $TiO_2$ particles, and were measured by a chemiluminescence (CL) technique using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[ 1,2-a]pyrazin-3-one (MCLA) as the reagent. The initial concentration of the ${H_2O_2}^./{O_2}^{-.}$ stream entering the KTR was determined by its half-life (98 s) at pH 5.8. We suggests that the efficiency of $TiO_2$ photocatalytic reactions may be further improved by utilizing the mobility of ${H_2O_2}^./{O_2}^{-.}$.

• Korean Journal of Materials Research
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• v.30 no.4
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• pp.211-216
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• 2020

Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors, because of their relatively low mobility, have limits in attempts to fulfill high-end specifications for display backplanes. In-Zn-O (IZO) is a promising semiconductor material for high mobility device applications with excellent transparency to visible light region and low temperature process capability. In this paper, the effects of working pressure on the physical and electrical properties of IZO films and thin film transistors are investigated. The working pressure is modulated from 2 mTorr to 5 mTorr, whereas the other process conditions are fixed. As the working pressure increases, the extracted optical band gap of IZO films gradually decreases. Absorption coefficient spectra indicate that subgap states increase at high working pressure. Furthermore, IZO film fabricated at low working pressure shows smoother surface morphology. As a result, IZO thin film transistors with optimum conditions exhibit excellent switching characteristics with high mobility (≥ 30㎠/Vs) and large on/off ratio.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.250-254
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• 2007

Applying the moving photo-carrier grating(MPG) technique and time-of-flight(TOF) measurements, we studied the transport properties of stabilized amorphous selenium typical of the material used in direct conversion X-ray imaging devices. For MPG measurement, we obtained electron and hole mobility and the recombination lifetime of $\alpha-Se$ films with arsenic(As) additions. We found an apparent increase in hole drift mobility and recombination lifetime, especially when 0.3 % As was added into $\alpha-Se$ film, whereas electron mobility decreased with the addition of As due to the defect density. For TOF measurement, a laser beam with pulse duration of 5 ns and wavelength of 350 nm was illuminated on the surface of $\alpha-Se$ with a thickness of 400 ${\mu}m$. The measured hole and electron transit times were about 8.73 ${\mu}s$ and 229.17 ${\mu}s$, respectively.

• Journal of Fashion Business
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• v.16 no.3
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• pp.13-31
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• 2012

The purpose of the study was to analyze the work clothes' clothing comfort and wearer mobility of painting workers with the consideration of the work environment features in the machine and shipbuilding industries in South Korea. A questionnaire survey was conducted for the study, which consisted of questions on the clothing comfort and wearer mobility aspects of painting work clothes by clothes types and body parts. The work clothes' clothing comfort and wearer mobility levels were scaled in 5 points i.e. 1(: very tight/very uncomfortable) to 5(: very slack/very comfortable). The painting work environmental hazardous features were considered as high impact levels of workplace temperature, oxygen deficiency, organic solvent, toxic gas factors while metal fragment factor only impacts 'low' in the painting processes with the findings throughout this study. Since the painting work consisted of surface washing and the spray and touch-up painting processes, which was carried out in an outdoor work place, the painting work clothes should meet high performance of waterproofing from the painting material and air permeability specially in summer as well as thermal performance in winter. The subjects painting workers' assessment of the existing work clothes' clothing oppression was in the levels between 3 (i.e. moderate) and 4 (i.e. comfortable) in a range of 1 to 5 points. The existing painting work clothes' wearer mobility was evaluated 'very uncomfortable' in all work clothes parts, especially, armhole length, biacromial breadth, sleeve length of the jumper; and body rise, waist, hip, thigh and knee circumferences of the pants.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2505-2511
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• 2014

Indium oxide nanocrystals ($In_2O_3$ NCs) with sizes of 5.5 nm-10 nm were synthesized by hot injection of the mixture precursors, indium acetate and oleic acid, into alcohol solution (1-octadecanol and 1-octadecence mixture). Field emission transmission electron microscopy (FE-TEM), High resolution X-Ray diffraction (X-ray), Nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FT-IR) were employed to investigate the size, surface molecular structure, and crystallinity of the synthesized $In_2O_3$ NCs. When covered by oleic acid as a capping group, the $In_2O_3$ NCs had a high crystallinity with a cubic structure, demonstrating a narrow size distribution. A high mobility of $2.51cm^2/V{\cdot}s$ and an on/off current ratio of about $1.0{\times}10^3$ were observed with an $In_2O_3$ NCs thin film transistor (TFT) device, where the channel layer of $In_2O_3$ NCs thin films were formed by a solution process of spin coating, cured at a relatively low temperature, $350^{\circ}C$. A size-dependent, non-monotonic trend on electron mobility was distinctly observed: the electron mobility increased from $0.43cm^2/V{\cdot}s$ for NCs with a 5.5 nm diameter to $2.51cm^2/V{\cdot}s$ for NCs with a diameter of 7.1 nm, and then decreased for NCs larger than 7.1 nm. This phenomenon is clearly explained by the combination of a smaller number of hops, a decrease in charging energy, and a decrease in electronic coupling with the increasing NC size, where the crossover diameter is estimated to be 7.1 nm. The decrease in electronic coupling proved to be the decisive factor giving rise to the decrease in the mobility associated with increasing size in the larger NCs above the crossover diameter.