• Title/Summary/Keyword: Thick Films

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Fabrication of Ceramic and Ceramic-Polymer Composite Thick Films by Aerosol Deposition Method (Aerosol Deposition Method을 응용한 세라믹 후막과 세라믹 -폴리머 복합체 후막 제작)

  • Cho, Sung-Hwan;Yoon, Young-Joon;Kim, Hyung-Jun;Kim, Hyo-Tae;Kim, Ji-Hoon;Nam, Song-Min;Baik, Hong-Koo;Kim, Jong-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.170-170
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    • 2009
  • aerosol deposition method(ADM)은 에어로졸화 된 고상의 원료분말을 노즐을 통해 분사시켜 소결과정을 거치지 않고도 상온에서 고밀도 후막을 제조할 수 있으며, 세라믹, 고분자, 금속 등의 다양한 코팅이 가능하다. 본 연구에서는 ADM들 이용하여 세라믹 후막 및 세라믹-폴리머 복합체 후막을 제조하였고 60 mm 노즐을 이용하여 대면적 세라믹 후막 성장도 시도되었다. 세라믹 후막의 원료로는 낮은 유전율과 우수한 품질계수를 갖는 $Al_2O_3$ 분말과 AlN의 분말이 사용되었으며, 세라믹에 비하여 높은 탄성과 1,500~2,000의 품질계수를 갖는 테프론(teflon) 분말이 세라믹과의 복합체 후막성장에 사용되었다. 세라믹-폴리머 복합체의 경우, 폴리머의 함유량에 따라 후막 내부의 결정립 크기가 20 때의 평균 결정립을 갚는 세라믹 후막에 비해 최대 10배 정도까지 증가하는 것을 확인할 수 있었으며, 이에 따라 후막에서의 유전특성 및 전기적인 특성, 열전도도, 투과율이 크게 변화하는 것을 확인할 수 있었다. 본 연구에서는 이러한 물성 변화에 대한 원인 고찰을 위하여 후막의 미세구조 및 화학조성 등에 다양한 분석이 이루어졌으며, 상온에서 성막되는 후막의 고분자 기판으로의 응용을 위한 최적의 공정조건을 제시하고자 한다.

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Fabrication of Sb-doped $SnO_2$ transparent conducting films by sol-gel dip coating and their characteristics (솔-젤 Dip Coating에 의한 Sb-doped $SnO_2$ 투명전도막의 제조 및 특성)

  • 임태영;오근호
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.5
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    • pp.241-246
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    • 2003
  • The transparent conducting thin film of ATO (antimony-doped tin oxide) was successfully fabricated on$SiO_2$/glass substrate by a sol-gel dip coating method. The crystalline phase of the ATO thin film was identified as SnO$_2$ major phase and the film thickness was about 100 nm/layer at the withdrawal speed of 50 mm/minute. Optical transmittance and electrical resistivity of the 400 nm-thick ATO thin film which was annealed under nitrogen atmosphere were 84% and $5.0\times 10^{-3}\Omega \textrm{cm}$, respectively. It was found that the $SiO_2$ layer inhibited Na ion diffusion and the formation of impurities like $Na_2SnO_3$ or SnO while increasing Sb ion concentration and higher ratio of $Sb^{5+}/Sb^{3+}$in the film. Annealing at nitrogen atmosphere leads to the reduction of $Sn^{4+}$ as well as $Sb^{5+}$ resulting in decrease of the electrical resistivity of the film.

Design of Highly Reliable Thick Film Gas Sensor Using SnO2 Nanofibers (SnO2 나노섬유를 이용한 고신뢰성 후막 가스센서 설계)

  • Jung, Jin Wook;Park, Sang Jin;Jeong, In Bong;Kim, Bo-Young;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.25 no.4
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    • pp.271-274
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    • 2016
  • The reliability and reproducibility of gas sensors are very important for real applications. The influence of nanofiber length and sensing film thickness on the reliability and response of gas sensing characteristics was investigated. For this, the length of $SnO_2$ nanofibers was controlled by tuning ultrasonic treatment and the different thicknesses of sensing films were prepared by manipulating the amount of slurry deposition. The sensor prepared from long nanofibers (length: ${\sim}3.6{\mu}m$) showed the significant fluctuation of gas sensing characteristics when the film becomes thinner than $18{\mu}m$, while that prepared from short nanofibers (length: ${\sim}0.9{\mu}m$) showed reproducible sensor response and resistance regardless of film thickness. Moreover, the shortening of nanofibers enhanced the gas response ~2 times, which can be explained by the increase of chemiresistive fiber-to-fiber contacts. The reproducibility, gas response, and selectivity of $SnO_2$ nanofiber gas sensor could be controlled by tuning nanofiber length, film thickness, and catalyst loading.

Sputtering yield of the MgO thin film grown on the Cu substrate by using the focused ion beam (집속이온빔을 이용한 구리 기판위에 성장한 MgO 박막의 스퍼터링 수율)

  • 현정우;오현주;추동철;최은하;김태환;조광섭;강승언
    • Journal of the Korean Vacuum Society
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    • v.10 no.4
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    • pp.396-402
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    • 2001
  • MgO thin films with 1000 $\AA$ thickness were deposited on Cu substrates by using an electron gun evaporator at room temperature. A 1000 $\AA$ thick Al layer was deposited on the MgO for removing the charging effect of the MgO thin film during the measurements of the sputtering yields. A Ga ion liquid metal was used as the focused ion beam(FIB) source. The ion beam was focused by using double einzel lenses, and a deflector was employed to scan the ion beams into the MgO layer. Both currents of the secondary particle and the probe ion beam were measured, and they dramatically changed with varying the applied acceleration voltage of the source. The sputtering yield of the MgO layer was determined using the values of the analyzed probe current, the secondary particle current, and the net current. When the acceleration voltage of the FIB system was 15 kV, the sputtering yield of the MgO thin film was 0.30. The sputtering yield of the MgO thin film linearly increases with the acceleration voltage. These results indicate that the FIB system is promising for the measurements of the sputtering yield of the MgO thin film.

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Studies on the Sensing Mechanism of Conducting Polymer for Volatile Organic Compound Sensing (휘발성 유기화합물 측정을 위한 전도성고분자 센서의 감응기구에 관한 연구)

  • Hwang, Ha-Ryong;Baek, Ji-Heum;Heo, Jeung-Su;Lee, Deok-Dong;Im, Jeong-Ok;Lee, Jun-Yeong
    • Korean Journal of Materials Research
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    • v.11 no.7
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    • pp.599-602
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    • 2001
  • In this study, we fabricated chemically polymerized PPy and PANi films with different selectivity by controlling dedoping time. And the sensing properties and mechanism of VOCs adsorption to conducting polymers were investigated. Thin sensor had higher sensitivity compared to thick one, and dedoped sensor for 1-minute highest sensitivity. Upon gas absorption, polypyrrole exhibited positive sensitivity while polyaniline had negative sensitivity. PPy film show hydrophilic property and PANi film show hydrophobic property. After the gas absorption, the sensitivity increased as a function of polarity of absorbed molecules. These behaviors are due to the polar molecules absorbed with the movable polaron or free carrier, and then it interrupt or generate the movement of polaron and carrier, and then it changes the conductivity of polymer. We found that conducting polymer sensors are very sensitive to the difference in polarity of gas molecules.

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Physical and Electrical Characteristics of Wet Oxidized LPCVD Silicon Nitride Films (습식 산화한 LPCVD Silicon Nitride층의 물리적, 전기적 특성)

  • Lee, Eun-Gu;Park, Jin-Seong
    • Korean Journal of Materials Research
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    • v.4 no.6
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    • pp.662-668
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    • 1994
  • The physical and electrical characteristics of sub-l0nm thick capacitor dielectrics formed by wet oxidation of silicon nitride(oxide/nitride composite) and by removing the top oxide of oxidized silicon nitride(0xynitride) are described. For the capacitors with an oxide/nitride composite layer, the capacitance decreases sharply, but the breakdown field increases with an increase in the wet oxidation time at $900^{\circ}C$. For the capacitors with oxynitride layers, the values of both the capacitance and the breakdown field increase with increasing wet oxidation time. The reduction of effective thickness and the improved quality of oxynitride film are responsible for the improved capacitance and increased breakdown fields, respectively. In addition, intrinsic TDDB characteristics and early breakdown failure rate of oxynitride film are improved with increasing oxidation time. Consequently, the oxynitride film is suitable for dynamic memories as a thin dielectric film.

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Gas Sensing Characteristics and Preparation of SnO2 Nano Powders (SnO2 나노 분말의 합성 및 가스 감응 특성)

  • Lee, Ji-Young;Yu, Yoon-Sic;Yu, Il
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.7
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    • pp.589-593
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    • 2011
  • [ $SnO_2$ ]nano powders were prepared by solution reduction method using tin chloride($SnCl_2{\cdot}2H_2O$), hydrazine($N_2H_4$) and NaOH. The $SnO_2$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and annealed at $300^{\circ}C$ in air, respectively. XRD patterns of the $SnO_2$ nano powders showed the tetragonal structure with (110) dominant orientation. The particle size of $SnO_2$ nano powders at the ratio of $SnCl_2:N_2H_4$+NaOH= 1:6 was about 60 nm. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a test box. Sensitivity of $SnO_2$ gas sensor to 5 ppm $CH_4$gas and 5 ppm $CH_3CH_2CH_3$ gas was investigated for various $SnCl_2:N_2H_4$+NaOH proportion. The highest sensitivity to $CH_4$ gas and $CH_3CH_2CH_3$ gas of $SnO_2$ sensors was observed at the $SnCl_2:N_2H_4$+NaOH= 1:8 and $SnCl_2:N_2H_4$+NaOH= 1:6, respectively. Response and recovery times of $SnO_2$ gas sensors prepared by $SnCl_2:N_2H_4$+NaOH= 1:6 was about 40 s and 30 s, respectively.

Film Thickness Dependence of Ac High Field for Low Density Polyethylene (저밀도 폴리에틸렌의 고전계 파형에 대한 필름 두께 의존성)

  • Choi, Yong-Sung;Wee, Sung-Dong;Hwang, Jong-Sun;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.04c
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    • pp.45-49
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    • 2008
  • Polyethylene is widely used as the insulator for power cable. To investigate the conduction mechanism for power cable insulation under ac high field, it is very important to acquire the dissipation current under actual running field. Recently, we have developed the unique system, which make possible to observe the nonlinear dissipation current waveform. In this system, to observe the nonlinear properties with high accuracy, capacitive current component is canceled by using inverse capacitive current signal instead of using the bridge circuit for canceling it. We have already reported that the dissipation currents of $40\;{\mu}m$ thick LDPE film at 10 kV/mm and over 140 Hz, it starts to show nonlinearity and odd number's harmonics were getting large. To investigate the conduction mechanis ms in this region, especially space charge effect, various kinds of estimation, such as time variations of instantaneous resistivity for one cycle, FFT spectra of dissipation current waveforms and so on, has been examined. As the results of these estimations, it was found that the dissipation current will depend on not only the instantaneous value of electric field but also the time differential of applied electric field due to taking a balance between applied field and internal field. Furthermore, two large peaks of dissipation current for each half cycle were observed under certain condition. In this paper, to clarify the reason why it shows two peaks for each half cycle, the film thickness dependences of dissipation current waveforms were observed by using the three different thickness LDPE films.

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Microstructure Analysis of Cu/Bi2212 High Temperature Superconducting Tapes with Meat-Treatment Atmosphere (열처리 분위기에 따른 동/Bi2212 고온초전도 테입의 미세구조)

  • Han, Sang-Chul;Sung, Tae-Hyun;Han, Young-Hee;Lee, Jun-Seong;Lee, Won-Tak;Kim, Sang-Jun
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.388-391
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    • 1999
  • Well oriented Bi2212 superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape method in which Cu-free BSCO powder mixture was' printed on copper plate and heat-treated. And we examined the effect of heat-treatment atmosphere for the superconducting properties and microstructure of Bi2212. The composition of Cu-free BSCO powder mixture was Bi$_2O_3$ : SrCO$_3$ : CaCO$_3$ = 1.2~2 : 1 : 1 and the heat-treatment for the superconducting formation reaction was performed in air, oxygen, nitrogen and low oxygen pressure. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Among the nonsuperconducting phases, it is known that the (Sr,Ca)CuO$_3$ phase restrain the formation of the Bi2212 superconducting phase. Because a kind of the nonsuperconducting phases is controled by the oxygen partial pressure, the optimum condition in which the remnants of the second phases don't leave in the fully processed conductor was determined by XRD and the critical tempera to re (Tc) analysis.

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Characteristics of Cobalt Silicide by Various Film Structures (다양한 박막층을 채용한 코발트실리사이드의 물성)

  • Cheong, Seong-Hwee;Song, Oh-Sung
    • Korean Journal of Materials Research
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    • v.13 no.5
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    • pp.279-284
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    • 2003
  • The $CoSi_2$ process is widely employed in a salicide as well as an ohmic layer process. In this experiment, we investigated the characteristics of $CoSi_2$ films by combinations of I-type (TiN 100$\AA$/Co 150$\AA$), II-type(TiN 100$\AA$/Co 150$\AA$/Ti 50$\AA$), III-type(Ti 100$\AA$/Co 150$\AA$/Ti 50$\AA$), and IV-type(Ti 100$\AA$/Co 150$\AA$/Ti 100$\AA$). Sheet resistances of $CoSi_2$ show the lowest resistance with 2.9 $\Omega$/sq. in a TiN/Co condition and much higher resistances in conditions simultaneously applying Ti capping layers and Ti interlayers. Though we couldn't observe a $CoSi_2$roughness dependence on the film stacks from RMS values, Ti capping layers turned into 78∼94$\AA$ thick TiN layers of (200) preferred orientation at $N_2$ambient. In addition, Ti interlayers helped to form the epitaxial $CoSi_2$with (200) preferred orientation and ternary compounds of Co-Ti-Si. We propose that film structures of II-type and III-type may be appropriate in the salicide process and the ohmic layer process from the viewpoint of Co diffusion kinetics and the CoSi$_2$epitaxy.