• Title, Summary, Keyword: Impedance spectroscopy

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In-situ Endpoint Detection for Dielectric Films Plasma Etching Using Plasma Impedance Monitoring and Self-plasma Optical Emission Spectroscopy with Modified Principal Component Analysis

  • Jang, Hae-Gyu;Chae, Hui-Yeop
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.153-153
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    • 2012
  • Endpoint detection with plasma impedance monitoring and self-plasma optical emission spectroscopy is demonstrated for dielectric layers etching processes. For in-situ detecting endpoint, optical-emission spectroscopy (OES) is used for in-situ endpoint detection for plasma etching. However, the sensitivity of OES is decreased if polymer is deposited on viewport or the proportion of exposed area on the wafer is too small. To overcome these problems, the endpoint was determined by impedance signal variation from I-V monitoring (VI probe) and self-plasma optical emission spectroscopy. In addition, modified principal component analysis was applied to enhance sensitivity for small area etching. As a result, the sensitivity of this method is increased about twice better than that of OES. From plasma impedance monitoring and self-plasma optical emission spectroscopy, properties of plasma and chamber are analyzed, and real-time endpoint detection is achieved.

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A 3kW Battery Charger with Battery Diagnosis Function Using Online Impedance Spectroscopy (온라인 임피던스 분광법을 이용한 배터리 진단 기능을 가진 3kW 충전기)

  • Doan, Van-Tuan;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • pp.68-69
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    • 2014
  • In the battery based applications such as electric vehicle and energy storage system, the performance of the system highly depends on the reliability of the battery. However, it is difficult to obtain the accurate information about the state-of-health (SOH) of battery during its operation. In this paper a 3kw battery charger with battery diagnosis function which can estimate the SOH of the battery by using online impedance spectroscopy technique is introduced. For the charger phase shift full bridge converter with synchronous rectification has been adopted to implement the charge and diagnosis functions. The impedance spectroscopy is performed after the charge to obtain the information about the internal impedance of the battery module, hence the SOH can be estimated online by observing the impedance variation of the battery over time. All the design procedure of the proposed charger is detailed and the feasibility of the system is verified by the experimental results.

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Consideration on the Non-linearity of Warburg Impedance for Fourier Transform Electrochemical Impedance Spectroscopy

  • Chang, Byoung-Yong
    • Journal of the Korean Electrochemical Society
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    • v.17 no.2
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    • pp.119-123
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    • 2014
  • Here I report on how Fourier Transform Electrochemical Impedance Spectroscopy (FTEIS) overcomes the potential-current linearity problem encountered in the impedance calculation process. FTEIS was first invented to solve the time-related drawback of the conventional impedance technique. The dramatic time reduction of FTEIS enabled the real-time impedance measurement but brought about the linearity problem at the same time. While the conventional method circumvents the problem using the steady-state made by a sufficiently long measurement time, FTEIS cannot because of its real-time function. However, according to the mathematical development reported in this article, the potential step used in FTEIS is proved to avoid the linearity problem. During the step period, the potential and the current are linearized by the electrochemical impedance. Also, Fourier transform of the differentiated potential and current is proved to give the same result of the original ones.

Corrosion Evaluation of Epoxy-Coated Bars by Electrochemical Impedance Spectroscopy

  • Choi, Oan-Chul;Park, Young-Su;Ryu, Hyung-Yun
    • International Journal of Concrete Structures and Materials
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    • v.2 no.2
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    • pp.99-105
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    • 2008
  • Southern exposure test specimens were used to evaluate corrosion performance of epoxy-coated reinforcing bars in chloride contaminated concrete by electrochemical impedance spectroscopy method. The test specimens with conventional bars, epoxy-coated bars and corrosion inhibitors were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. The polarization resistance obtained from the Nyquist plot was the key parameter to characterize the degree of reinforcement corrosion. The impedance spectra of specimens with epoxy-coated bars are mainly governed by the arc of the interfacial film and the resistance against the charge transfer through the coating is an order of magnitude higher than that of the reference steel bars. Test results show good performance of epoxy-coated bars, although the coatings had holes simulating partial damage, and the effectiveness of corrosion-inhibiting additives. The corrosion rate obtained from the impedance spectroscopy method is equivalent to those determined by the linear polarization method for estimating the rate of corrosion of reinforcing steel in concrete structures.

A Study on the Electrochemical Behavior of Carbon Material with Compact Surface Using Impedance Spectroscopy (조밀한 표면조직을 갖는 탄소재료의 Impedance Spectroscopy를 통한 전기화학적 거동의 해석)

  • Oh, Han Jun;Lee, Jong Ho;Lee, Young Hoon;Ko, Young Shin
    • Journal of the Korean Chemical Society
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    • v.40 no.5
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    • pp.308-316
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    • 1996
  • The electrochemical behavior of glassy carbon and PVDF synthesis graphite materials with compact surface have been characterized by impedance spectroscopy. The Faraday-impedance both carbon materials were depended highly on polarization and the difference of electrochemical behavior accord to structure of surface between glassy carbon and synthesis graphite was represented, in these evaluated equivalent circuits, PVDF synthesis graphite was indicated with form that is added resistance and capacitance by the hydrophobic binder to glassy carbon equivalent circuit.

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Application of Impedance Spectroscopy to Cement-Based Materials: Hydration of Calcium Phosphate Bone Cements

  • Kim, Sung-Moon;Hwang, Jin-Ha
    • Journal of the Korean Ceramic Society
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    • v.43 no.3
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    • pp.156-161
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    • 2006
  • Impedance spectroscopy was applied to the initial hydration of calcium phosphate bone cements in order to investigate the electrical/dielectric properties. Hydration or equivalently setting was monitored as a function of the amount of water and initial powder characteristics. Higher amounts of water produced more open microstructures, leading to higher conductivity and enhanced dielectric constant. The effects of the initial characteristics in the powder were investigated using bone cement powder prepared with and without granulation. Granulated powder exhibited a significant change in resistance and produced a higher dielectric constant than those of conventional powder. Through a simplified modeling, the effects of thickness in reaction products and pore sizes were estimated by the frequency-dependent impedance measurements. Furthermore, impedance spectroscopy was proven to be a highly reliable tool for evaluating the continuous change in pore structure occurring in calcium phosphate bone cements.

Setting Characteristic Assessment of Cementitious Materials using Electrical Impedance Spectroscopy (전기 임피던스 분광법을 이용한 시멘트계 재료의 응결 특성 평가)

  • Lee, Jun-Cheol;Park, In-Yong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.474-480
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    • 2017
  • In this study, the evolution of electrical impedance of electric nodes was investigated to determine the setting time of cement paste using the electrical impedance spectroscopy method. The electric nodes were embedded in fresh cement paste and the electrical impedance signatures were continuously monitored. Vicat needle test and semi-adiabatic calorimetry test were also conducted to validate the electrical impedance spectroscopy method. During hydration period of cement paste, the magnitude of conductance gradually increased, and then started to decrease rapidly at a first certain time. After that, the magnitude of conductance gradually decreased at a second certain time. The times of turning point in the curves of magnitude of conductance seem to be related with the setting time by Vicat needle test. Also, the setting times by the electrical impedance spectroscopy method are well posed within the setting period estimated by the semi-adiabatic calorimetry test. Based on the results, it can be concluded that the setting time of cement paste can be effectively monitored through the electrical impedance spectroscopy method.

Proton Conductivity Measurement Using A.C. Impedance Spectroscopy for Proton Exchange Membrane

  • Lee, Chang Hyun;Park, Ho Bum;Lee, Young Moo
    • Korean Membrane Journal
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    • v.6 no.1
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    • pp.1-9
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    • 2004
  • The impedance and the subsequent proton conductivity of Nafion$\^$/ membranes as standard samples were measured and compared via the two-probe method and the four-probe method using the prepared impedance measurement system. The different impedance behavior for the same membrane was observed at the fully hydrated state in the Nyquist impedance plot. The effect of the humidity and the temperature on the proton conduction through a membrane was investigated and compared with two different cell configurations.

Analysis of Main Design Factors for Developing a Soil Water Content Sensor Using Impedance Spectroscopy (Impedance Spectroscopy를 이용한 토양 수분함량 센서의 주요 설계인자 분석)

  • Lee, Dong-Hoon;Cho, Yong-Jin;Chang, Young-Chang;Lee, Kyou-Seung
    • Journal of Biosystems Engineering
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    • v.33 no.4
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    • pp.269-275
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    • 2008
  • This study was conducted to design an impedance sensor that can measure soil water content of soils. Partial least square regression (PLSR) was applied to soil impedance data preprocessed with a smoothing method. An optimal sub-spectrum size and wavelength range were determined by comparing the coefficient of determination ($R^2$) and root mean square error (RMSE) of the PLSR models obtained using soil impedance data. various PLS analysis. Based on the PLSR analysis, it would be concluded that the optimal spectrum measurement range was $32.0{\sim}50.0\;MHz$ with the optimal sub-spectrum size of about 18.5 MHz.

Impedance spectroscopy for lifetime analysis of OLED

  • Yoon, Chul-Oh;Kim, Hyun-Chul;Yi, Seok-Kyung;Kong, Ung-Gul;Lee, Nam-Heon;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.137-140
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    • 2002
  • The frequency response analysis of complex impedance spectra using small perturbation ac impedance spectroscopy is an informative method of OLED performance characterization and lifetime analysis. Using simple RC equivalent circuit mode,l macroscopic nonliniear transport properties of semiconductive emission/transport layers can be analyzed and parameterized. We present the bias voltage dependence and aging effect in impedance spectra measured from an ITO/CuPC/TPD/$Alq_3$/LiF/Al OLED device, and discuss possible failure mechanism based on impedance model parameters.

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