• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.164-168
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• 2005

We report high performance poly (3-hexylthiophene) organic field-effect transistors fabricated on a plastic substrate. The polymer active channel layer was directly printed by the rubber stamp printing method with a pre-patterned elastomer stamp. As a result. organic transistors having average field-effect mobility of 0.079 $cm^2/Vs$ and on/off ratio of $10^4{\sim}10^5$ were realized on a plastic substrate. Also, through the investigation of the molecular ordering of rubber-stamp-printed poly (3-hexylthiophene) films using synchrotron grazing-incidence X-ray diffraction measurements, the films were found to have edge-on structure which is favorable in realizing high performance organic transistors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.263-271
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• 2010

e-Printing is a new manufacturing technology for electronic products and is based on traditional printing technology. The electronic products require a large area to facilitate printing and to be economical. A gravure printing system that supports a roll to roll (R2R) manufacturing process can be used to reduce the cost and to achieve the required accuracy. Many factors such as drying method, drying temperature, tension,-printing velocity, ink viscosity, ink conductivity, pattern accuracy, and dot geometry influence the performance of printed electronics. These factors are closely interrelated. The optimum condition for printing must be determined to enhance the performance of the printed electronics. In this study, lines and areas are printed using a gravure printer with conductive ink under different conditions of the above mentioned factors. The results are analyzed to investigate the influence of various factors on the performance of the printed electronics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.617-621
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• 2013

This study examined the effect of electron-beam (E-beam) irradiation on the electrical properties of n-GaN, AlGaN and AlGN/GaN structures on sapphire substrates. E-beam irradiation resulted in a significant decrease in the gate leakage current of the n-GaN, AlGaN and HEMT structure from $4.0{\times}10^{-4}A$, $6.5{\times}10^{-5}A$, $2.7{\times}10^{-8}A$ to $7.7{\times}10^{-5}A$, $7.7{\times}10^{-6}A$, $4.7{\times}10^{-9}A$, respectively, at a drain voltage of -10V. Furthermore, we also investigated the effect of E-beam irradiation on the AlGaN surface in AlGaN/GaN heterostructure high electron mobility transistors(HEMTs). The results showed that the maximum drain current density of the AlGaN/GaN HEMTs with E-beam irradiation was greatly improved, when compared to that of the AlGaN/GaN HEMTs without E-beam irradiation. These results strongly suggest that E-beam irradiation is a promising method to reduce leakage current of AlGaN/GaN HEMTs on sapphire through the neutralization the trap.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.243-246
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• 2008

Roll-printed organic thin-film transistors (OTFTs) were fabricated by gravure or flexography printing using patterned PDMS stamp with various channel lengths, silver pastes, coated polyvinylphenol dielectric, and jetted bis(triisopropyl-silylethynyl) pentacene semiconductor on plastic substrates. The roll-printed OTFT parameters were obtained: fieldeffect mobility of $0.1\;cm^2/Vs$, an on/off current ratio of $10^4$ and a subthreshold slope of 2.53 V/decade.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.1-7
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• 2023

The ability of 3D/4D printing technology to create arbitrary 3D structures provides a greater degree of freedom in the design of printed structures. This capability has influenced the field of electronics and biomedical applications by enabling the trends of device miniaturization, customization, and personalization. Here, the current state-of-the-art knowledge of 3D printed electronics and biomedical applications with the unique and unusual properties enabled by 3D/4D printing is reviewed. Specifically, the review encompasses emerging areas involving recyclable and degradable electronics, metamaterial-based pressure sensor, fully printed portable photodetector, biocompatible and high-strength teeth, bioinspired microneedle, and transformable tube array for 3D cell culture and histology.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.67-72
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• 2011

8-layer printed circuit board is designed and implemented for triple band(2.3/2.5/3.5GHz) m-WiMAX system. In order to maintain excellent RF performance, low dielectric constant material is used for implementation of the printed circuit board. Also, embedded printed circuit board which embed passive devices is manufactured to reduce total system area. As a result, total system area is cut off by 9%. Triple band m-WiMAX system is produced using embedded printed circuit board. Furthermore, internet connecting test is performed and proved successful running of the system. The developed embedded printed circuit board will provide a effective solution for system area reduction and low loss signal RF communication system.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1312-1314
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• 2007

The effect of gate insulator surface treatment on electrical characteristics of bottom contact (BC) and suspended source/drain (SSD) organic thinfilm transistors (OTFTs) was studied. Triisopropylsilylethynyl pentacene was used as an active material and was printed by ink-jet printing method. In case of the BC OTFTs, threshold voltage was shifted from positive to near zero, and the fieldeffect mobility was increased when the gate insulator surface was treated with hexamethyldisilazane. However, in case of SSD OTFT, threshold voltage shift was not observed and the field-effect mobility was decreased.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.147-150
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• 2014

Copper ink has been prepared by mixing copper(II) formate and 2-ethyl-1-hexylammonium bicarbonate (EHABC) to overcome some weak points such as aggregation and degradation of copper nano-type ink. Ink was coated on glass substrate and calcined at $110^{\circ}C$ to $150^{\circ}C$ to generate electrically conductive copper film under two different atmospheres such as nitrogen gas and gaseous mixture of formic acid and methanol. The lowest resistivity of $1.88{\mu}{\Omega}{\cdot}cm$ of copper film was obtained at $150^{\circ}C$ in gaseous formic acid condition. The long-term resistivity shows to increase from $1.88{\mu}{\Omega}{\cdot}cm$ to $2.61{\mu}{\Omega}{\cdot}cm$ after one month.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.209.1-209.1
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• 2005

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.18-23
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• 1998

Development of an automobile antenna printed on-glass for FM radio receptions was discussed in this study. NEC-2 code was used as the design tool in this research. An omnidirectional radiation pattern and reception power level of the newly designed antenna were compared with those of the conventional pole antenna for the evaluation of its performance. The test sites for the reception power level measurement were chosen by their signal enbironmental condition, such as multipath fading, and strong field effect area.