• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.278.1-278.1
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• 2014

Organic materials have been explored as the gate dielectric layers in thin film transistors (TFTs) of backplane devices for flexible display because of their inherent mechanical flexibility. However, those materials possess some disadvantages like low dielectric constant and thermal resistance, which might lead to high power consumption and instability. On the other hand, inorganic gate dielectrics show high dielectric constant despite their brittle property. In order to maintain advantages of both materials, it is essential to develop the alternative materials. In this work, we manufactured nanocomposite gate dielectrics composed of organic material and inorganic nanoparticle and integrated them into organic TFTs. For synthesis of nanocomposite gate dielectrics, polyimide (PI) was explored as the organic materials due to its superior thermal stability. Candidate nanoprticles (NPs) of halfnium oxide, titanium oxide and aluminium oxide were considered. In order to realize NP concentration dependent electrical characteristics, furthermore, we have synthesized the different types of nanocomposite gate dielectrics with varying ratio of each inorganic NPs. To analyze gate dielectric properties like the capacitance, metal-Insulator-metal (MIM) structures were prepared together with organic TFTs. The output and transfer characteristics of organic TFTs were monitored by using the semiconductor parameter analyzer (HP4145B), and capacitance and leakage current of MIM structures were measured by the LCR meter (B1500, Agilent). Effects of mechanical cyclic bending of 200,000 times and thermally heating at $400^{\circ}C$ for 1 hour were investigated to analyze mechanical and thermal stability of nanocomposite gate dielectrics. The results will be discussed in detail.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.361-361
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• 2012

PZT (Pb(Zr,Ti)O3) thin films have been used widely in the MEMS application, due to their inherent ferroelectric and piezoelectric properties. Such ferroelectricity induces much higher dielectric constants compared to those of the nonperovskite materials. In this work, the PZT thin films were deposited onto Indium-Tin-oxide (ITO) substrates through the spin-coating of PZT sols. The deposited PZT thin films were characterized in terms of the electrical and optical properties with special emphases on conductivity and optical constants. The detailed analysis techniques incorporate the dc-based current-voltage characteristics for the electrical properties, spectroscopic ellipsometry for optical characterization, atomic force microscopy for surface morphology, X-ray Photoelectron Spectroscopy for chemical bonding, Energy-dispersive X-ray Spectrometry for chemical analyses and X-ray diffraction for crystallinity. The ferroelectric phenomena were confirmed using capacitance-voltage measurements. The integrated physical/chemical features are attempted towards energy-oriented applications applicable to next-generation high-efficiency power generation systems.

• 한국정보통신학회논문지
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• 제10권10호
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• pp.1835-1841
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• 2006

해양환경 규제 MEPC의 규제 강화로 인하여 더욱 정밀하고, 신뢰성을 확보한 빌지분리 센서 시스템이 필요하다. 빌지 분류기를 설계 제작하기 위해서는 기름과 물을 구별하는 정밀한 유수분리 레벨센서가 필요하다. 이를 위하여 본 연구에서는 정전용량형 레벨센서의 특성 파악을 위해 3차원 시뮬레이션을 수행하여 특성을 파악하였으며, 이를 토대로 레벨센서의 설계시 주요한 설계인자를 추출하였다. 동작회로를 Digital 회로로 구성함으로써, 정전용량형 센서의 원천적인 기생커패시턴스 문제를 해결하였으며, 실험장치를 구성한 후 실험을 수행하였다. 실험 결과를 보면 노이즈에는 강인해졌음을 알 수 있었다. 그리고 추출한 정전용량형 레벨센서의 설계인자를 이용하여 정밀도를 향상시키기 위한 연구가 향후에 진행 될 필요성이 있다.

• Journal of Power Electronics
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• 제6권1호
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• pp.73-82
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• 2006

Plasma display panels (PDPs) have a serious thermal problem, because the luminance efficiency of a conventional PDP is about 1.5 1m/W and it is less than $3\~5\;lm/W$ of a cathode ray tube (CRT). Thus there is a need for improving the luminance efficiency of the PDP. There are several approaches to improve the luminance efficiency of the PDP and we adopted a driving PDP at high frequency range from 400kHz up to over 700kHz. Since a PDP is regarded as an equivalent inherent capacitance, many types of sustaining drivers have been proposed and widely used to recover the energy stored in the PDP. However, these circuits have some drawbacks for driving PDPs at high frequency ranges. In this paper, we investigate the effect of the parasitic components on the PDP itself and on the driver when the reactive energy of the panel is recovered. Various drivers are classified and evaluated based on their suitability for high frequency drivers. Finally, a current-fed driver with a DC input voltage bias is proposed. This driver overcomes the effect of parasitic components in the panel and driver. It fully achieves a ZVS of all full-bridge switches and reduces the transition time of the panel polarity. It is tested to validate the high frequency sustaining driver and the experimental results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.380-384
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• 2005

Plasma display panel (PDP) has a serious thermal problem, because the luminance efficiency of the conventional PDP is about 1.5 lm/W and it is less than $3{\sim}5$ lm/W of cathode ray tube (CRT). Thus there is a need for improving the luminance efficiency of the PDP There are several approaches to improve the luminance efficiency of the PDP and we adopt the driving PDP at high frequency range from 400 kHz up to over 700 kHz. Since a PDP is regarded as an equivalent inherent capacitance, many types of sustaining drivers have been proposed and widely used to recover the energy stored in the PDP. However, these circuits have some drawbacks for driving PDP at high frequency range. In this paper, we investigate the effect of the parasitic components of PDP itself and driver when the reactive energy of panel is recovered. Various drivers are classified and evaluated whether it is suitable for high frequency driver, and finally current-fed type with do input voltage biased is proposed. This driver overcomes the effect of parasitic component in panel and driver and fully achieves ZVS of all full-bridge switches and reduces the transition time of the panel polarity.