• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.785-789
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• 2013

Silicon Carbide (SiC) is the material with the wide band-gap (3.26 eV), high critical electric field (~2.3 MV/cm), and high bulk electron mobility (~900 $cm^2/Vs$). These electronic properties allow attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation compared to Si devices. In general, device design has a significant effect on the switching and electrical characteristics. It is known that in this paper, we demonstrated that the switching performance and breakdown voltage of IGBT is dependent with doping concentration of p-base region and drift layer by using 2-D simulations. As a result, electrical characteristics of SiC-IGBT deivce is higher breakdown voltage ($V_B$= 1,600 V), lower on-resistance ($R_{on}$= 0.43 $m{\Omega}{\cdot}cm^2$) than Si-IGBT. Also, we determined that processing time and cost is reduced by the depth of n-drift region of IGBT was reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.518-520
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• 1997

Recently, thiophene oligomer with short chain lengths has received much attention as model compounds for facilitating better understanding of electronic and optical properties of polymers, because oligomer is well-defined chemical systems and its conjugation chain length can be exactly controlled. Moreover, organic this films based on conjugated thiophene oligomer have potential for application to electronic and optoelectronic devices such as MISFETs(metal-insulator-semiconductor field-effect transistors) and LEDs(light-emitting diodes). However, there is little knowledge on electronic and structural properties of linear-conjugated oligothiophenes in solid states, compared with those in solutions. $\alpha$-sexithienyl($\alpha$-6T) thin-films were deposited by OMBD(Organic Molecular Beam Deposition) technique, where the $\alpha$-6T was synthesized and purified by the sublimation method. The $\alpha$-6T films were deposited under various conditions. The effects of deposition rate, substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecules in the $\alpha$-6T film deposited at a low deposition rate under a high vacuum were aligned almost perpendicular to the substrate. The $\alpha$-6T films deposited at an elevated substrate temperature showed higher conductivity than the film deposited at room temperature. Electrical characterization of these films will be also executed by using four-point probe measurement technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.120-121
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• 2007

Nano-floating gate memory (NFGM) devices were fabricated by using the low temperature poly-Si thin films crystallized by ELA and the $In_2O_3$ nano-particles embedded in polyimide layers as charge storage. Memory effect due to the charging effects of $In_2O_3$ nano-particles in polyimide layer was observed from the TFT NFGM. The post-annealing in 3% diluted hydrogen $(H_2/N_2)$ ambient improved the retention characteristics of $In_2O_3$ nano-particles embedded poly-Si TFT NFGM by reducing the interfacial states as well as grain boundary trapping states.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.15-16
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• 2005

Chalcogenide phase change memory has high performance to be next generation memory, because it is a nonvolatile memory processing high programming speed, low programming voltage, high sensing margin, low consumption and long cycle duration. We have developed a new material of PRAM with $Ge_1Se_1Te_2$. This material has been propose to solve the high energy consumption and high programming current. We have investigated the phase transition behaviors in function of various process factor including contact size, cell size, and annealing time. As a result, we have observed that programming voltage and writing current of $Ge_1Se_1Te_2$ are more improved than $Ge_2Sb_2Te_5$ material.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.268-276
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• 2021

As wireless communication devices become more common, interests in how to control the electromagnetic waves generated from the devices are increasing. One of the most commonly used electromagnetic wave control materials is magnetic one, but due to the features that make the product heavy and thick when applied to the product, it is difficult to use them in curved electronic devices. Therefore, a polymer flexible meta electronic device has been presented to sort out the problem, which is thin and can have various curvatures. However, it requires an additional evaluation of curvature reliability. In this study, we developed a method to predict electromagnetic wave control characteristics through the resistance/length of the conductive ink line patterns of polymer flexible meta electronic devices, which is inversely proportional to the electromagnetic wave control characteristics. As the radius of curvature decreased, the resistance/length increased, and there was little variations with the duration times of curvature. We also found that both permanent and recoverable changes along with the removal of curvature were occurred when the curvature was applied, and that the cause of these changes was newly created vertical cracks in the conductive ink line pattern due to the tensile stress applied by applying curvature.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.366-370
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• 2019

In this study, we have successfully fabricated a highly conductive transparent electrode using Ag nanowires, based on piezoelectric polyvinylidene difluoride (PVDF) film, that can be applied as transparent and flexible speakers. The structural morphology of the Ag nanowires was confirmed by a detailed scanning electron microscopy. Ultraviolet-visible spectroscopy demonstrated that the transparent electrode fabricated by the Ag nanowires exhibited a transmittance of above 70%. The transparent electrode also showed very low sheet resistance with high flexibility. We have further developed an anti-oxidation coating layer by using a tetraethyl orthosilicate-poly trimethyloxyphenylsilane (TEOS-PTMS) slurry technique. It was confirmed that the transmittance and sheet resistance of the antioxidant film depends critically on the humidity of the film surface. We believe such Ag nanowire electrodes are a very promising next-generation transparent electrode technology that can be used in future flexible and transparent devices.

• Advances in nano research
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• v.12 no.2
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• pp.151-165
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• 2022

Micro-scale serpentine structure fibers are widely used as flexible sensor in the manufacturing of micro-nano flexible electronic devices because of their outstanding non-linear mechanical properties and organizational flexibility. The use of melt electrowriting (MEW) technology, combined with the axial bending effect of the Taylor cone jet in the process, can achieve the micro-scale serpentine structure fibers. Due to the interference of the process parameters, it is still challenging to achieve the precise deposition of micro-scale and high-consistency serpentine structure fibers. In this paper, the micro-scale serpentine structure fiber is produced by MEW combined with axial bending effect. Based on the controlled deposition of MEW, applied voltage, collector speed, nozzle height and nozzle diameter are adjusted to achieve the precise deposition of micro-scale serpentine structure fibers with different morphologies in a single motion dimension. Finally, the influence mechanism of the above four parameters on the precise deposition of micro-scale serpentine fibers is explored.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.3
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• pp.45-56
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• 2012

Printing technology is accepted by appropriate technology that smart phones, tablet PC, display(LCD, OLED, etc.) precision recently in the electronics industry, the market grows, this process in the ongoing efforts to improve competitiveness through the development of innovative technologies. So printed electronics appeared by new concept. This technology development is applied on electronic components and circuits for the simplification of the production process and reduce processing costs. Low-temperature process making possible for widening, slimmer, lighter, and more flexible, plastic substrates, such as(flexible) easily by forming a thin film on a substrate has been studied. In the past, the formation of the electrode used a screen printing method. But the screen printing method is formation of fine patterns, high-speed printing, mass production is difficult. The roll-to-roll printing method as an alternative to screen printing to produce electronic devices by printing techniques that were used traditionally in the latest technology and processing techniques applied to precision control are very economical to implement fine-line printing equipment has been evaluated as. In order to function as electronic devices, especially the dozens of existing micro-level of non-dot print fine line printing is required, the line should not break at all, because according to the specifications required to fit the ink transfer conditions should be established. In this study of roll-to-roll printing conductive paste suitable for gravure offset printing by developing Ag paste for forming fine patterns to study the basic physical properties with the aim of this study were to.

• Transactions of the KSME C: Technology and Education
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• v.4 no.1
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• pp.63-71
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• 2016

Although mechatronics education in a mechanical engineering curriculum is recently recognized as important, its experimental education has been done generally in the laboratory equipped with all the apparatus and could not be done at home by students. This paper introduces experimental educations on mechatronics, e.g., digital logic circuits, 7-segment LED drive, square wave generation, microcontroller programming using assembly and C languages, timer interrupt, and step motor drive using a small 5 V power supply, a breadboard, various electronic and electric components, a microcontroller and its programmer, a step motor, and a student's PC. In the developed mechatronics course, experimental educations are scheduled in parallel with content's lectures together, and cheap and economic experimental environment is prepared for students in which students can easily practice experimental works in advance or later at home by themselves.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.294.1-294.1
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• 2016

Transition metal dichalcogenides (TMDs) with two-dimensional layered structure, such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2), are considered attractive materials for future semiconductor devices due to its relatively superior electrical, optical, and mechanical properties. Their excellent scalability down to a monolayer based on the van der Waals layered structure without surface dangling bonds makes semiconductor devices based on TMD free from short channel effect. In comparison to the widely studied transistor based on MoS2, researchs focusing on WSe2 transistor are still limited. WSe2 is more resistant to oxidation in humid ambient condition and relatively air-stable than sulphides such as MoS2. These properties of WSe2 provide potential to fabricate high-performance filed-effect transistor if outstanding electronic characteristics can be achieved by suitable metal contacts and doping phenomenon. Here, we demonstrate the effect of two different metal contacts (titanium and platinum) in field-effect transistor based on WSe2, which regulate electronic characteristics of device by controlling the effective barreier height of the metal-semiconductor junction. Electronic properties of WSe2 transistor were systematically investigated through monitoring of threshold voltage shift, carrier concentration difference, on-current ratio, and field-effect mobility ratio with two different metal contacts. Additionally, performance of transistor based on WSe2 is further enhanced through reliable and controllable n-type doping method of WSe2 by triphenylphosphine (PPh3), which activates the doping phenomenon by thermal annealing process and adjust the doping level by controlling the doping concentration of PPh3. The doping level is controlled in the non-degenerate regime, where performance parameters of PPh3 doped WSe2 transistor can be optimized.