• Title/Summary/Keyword: 디스플레이 특성화

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Low-voltage Pentacene Field-Effect Transistors Based on P(S-r-BCB-r-MMA) Gate Dielectrics (P(S-r-BCB-r-MMA) 게이트 절연체를 이용한 저전압 구동용 펜타센 유기박막트랜지스터)

  • Koo, Song Hee;Russell, Thomas P.;Hawker, Craig J.;Ryu, Du Yeol;Lee, Hwa Sung;Cho, Jeong Ho
    • Applied Chemistry for Engineering
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    • v.22 no.5
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    • pp.551-554
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    • 2011
  • One of the key issues in the research of organic field-effect transistors (OFETs) is the low-voltage operation. To address this issue, we synthesized poly(styrene-r-benzocyclobutene-r-methyl methacrylate) (P(S-r-BCB-r-MMA)) as a thermally cross-linkable gate dielectrics. The P(S-r-BCB-r-MMA) showed high quality dielectric properties due to the negligible volume change during the cross-linking. The pentacene FETs based on the 34 nm-thick P(S-r-BCB-r-MMA) gate dielectrics operate below 5 V. The P(S-r-BCB-r-MMA) gate dielectrics yielded high device performance, i.e. a field-effect mobility of $0.25cm^2/Vs$, a threshold voltage of -2 V, an sub-threshold slope of 400 mV/decade, and an on/off current ratio of ${\sim}10^5$. The thermally cross-linkable P(S-r-BCB-r-MMA) will provide an attractive candidate for solution-processable gate dielectrics for low-voltage OFETs.

Fabrication of a Novel Ultra Low Temperature Co-fired Ceramic (ULTCC) Using BaV2O6 and BaWO4 (BaV2O6와 BaWO4을 이용한 초저온 동시소성 세라믹 제조)

  • Kim, Duwon;Lee, Kyoungho
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.4
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    • pp.11-18
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    • 2021
  • A novel microwave dielectric composite material for ultra-low temperature co-fired ceramics (ULTCC) with (1-x)BaWO4-xBaV2O6 (x=0.54~0.85) composition was prepared by firing a mixture of BaWO4 and BaV2O6. Shrinkage tests showed that the ceramic composite begins to densify at a temperature as low as 550℃ and can be sintered at 650℃ with 98% of relative density under the influence of BaV2O6. X-ray diffraction analysis showed that BaWO4 and BaV2O6 coexisted and no secondary phase was detected in the sintered bodies, implying good chemical compatibility between the two phases. Near-zero temperature coefficients of the resonant frequency (𝛕f) could be achieved by controlling the relative content of the two phases, due to their positive and negative 𝛕f values, respectively. With increasing BaV2O6 (x from 0.53 to 0.85), the 𝛕f value of the composites increased from -7.54 to 14.49 ppm/℃, εr increased from 10.08 to 11.17 and the quality factor (Q×f value) decreased from 47,661 to 37,131 GHz. The best microwave dielectric properties were obtained for x=0.6 samples with εr=10.4, Q×f=44,090 GHz, and 𝛕f=-2.38 ppm/℃. Chemical compatibility experiments showed the developed composites are compatible with aluminum electrode during co-firing process.

Dehydration of Lactic Acid to Bio-acrylic Acid over NaY Zeolites: Effect of Calcium Promotion and KOH Treatment (NaY 제올라이트 촉매 상에서 젖산 탈수반응을 통한 바이오아크릴산 생산: Ca 함침 및 KOH 처리 영향)

  • Jichan, Kim;Sumin, Seo;Jungho, Jae
    • Clean Technology
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    • v.28 no.4
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    • pp.269-277
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    • 2022
  • With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH3- and CO2-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.