• 한국표면공학회지
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• 제25권3호
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• pp.126-132
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• 1992

Recent VLSI requires materials with high dielectric constant in order to reduce their storage capacitor areas. Thin TaOx film was formed from Ta(OCH3)5 by photo-CVD method at a low temperature. The result shows that the film obtained by photo-CVD method is this study has good step coverage, high dielectric constant (20-25) and low leakage current. The high strong peaks from Ta(4f), Ta(4d), and O(ls) levels were observed by XPS analysis. From the diffraction pattern and TEM prcture analysis, the TaOx thin film was observed to be amorphous. This kind of the deposition method could be considered to be a very promising method applied to VLSI.

• 한국전기전자재료학회논문지
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• 제20권1호
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• pp.8-13
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• 2007

In MIS capacitor structure, we have studied the electrical properties in Ammonium Sulfide solution treatment while AIN thin film as a insulator is being formed by reactive sputtering method. The deposition process conditions of AIN thin film we temperature $250^{\circ}C$, DC Power 150 W, pressure 5 mTorr and 8 sccm(Ar : 4 sccm, $N_{2}$ : 4 sccm). The surface of GaAs was treated with Ammonium Sulfide solution, it was shown the leakage current was less than $10^{-8}\;A/cm^{2}$. The deep depletion phenomena of inverse area with treating Ammonium Sulfide solution in C-V analysis was improved as compared the condition of without Ammonium Sulfide solution and hysteresis property as well.

• 공업화학
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• 제17권4호
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• pp.335-342
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• 2006

금속 알루미늄의 낮은 환원전위는 전기화학적 산화반응을 통하여 알루미늄과 그 표면에 존재하는 산화막의 구조 및 성질의 변화를 일으킨다. 산성용액에서 알루미늄을 전기화학적으로 에칭하여 표면적을 확대시키고 중성의 용액에서 알루미늄 표면에 치밀한 유전체 산화막을 형성시켜 커패시터의 전극으로 이용하고 있다. 저온의 산성용액에서는 양극산화시 나노크기의 다공층 산화막이 형성되며, 나노구조체의 템플레이트로 사용되고 있다. 이와같은 알루미늄의 전기화학적 특성은 알루미늄을 새로운 기능성을 가진 재료로 변화시킴으로서 다양한 분야에서 응용될 것으로 기대된다.

• 전기학회논문지P
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• 제66권4호
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• pp.236-241
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• 2017

This paper presents a single-phase grid connected voltage-ed inverter with a power decoupling circuit. In the single-phase grid connected voltage-ed inverter, it is well known that a power pulsation with twice the grid frequency is contained in the input power. In a conventional voltage type inverter, electrolytic capacitors with large capacitance have been used in order to smooth the DC voltage. However, lifetime of those capacitors is shortened by the power pulsation with twice grid frequency. The authors have been studied a active power decoupling(APD) method that reduce the pulsating power on the input DC bus line, this enables to transfer the ripple energy appeared on the input DC capacitors into the energy in a small film capacitor on the additional circuit. Hence, extension of the lifetime of the inverter can be expected because the small film capacitor substitutes for the large electrolytic capacitors. Finally, simulation and experimental results are discussed.

• 대한전자공학회논문지SD
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• 제48권3호
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• pp.1-6
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• 2011

N-channel 산화물 박막 트랜지스터(Thin Film Transistor, 이하 TFT)만을 이용한 저소비전력 inverter, NAND, NOR의 논리 게이트 회로를 제안한다. 제안된 회로는 asymmetric feed-through와 bootstrapping을 이용해서 pull-up, pull-down 스위치가 동시에 켜지지 않도록 설계하였다. 그 결과로 출력신호 전압 범위가 입력신호 전압과 동일하고 정전류가 흐르지 않는다. 인버터는 5 개의 TFT와 2 개의 capacitor로, NAND 및 NOR 게이트는 각각 10 개의 TFT와 4 개의 capacitor로 구성된다. 산화물 TFT 모델을 사용하여 SPICE 시뮬레이션을 수행하여 제안된 회로의 동작을 성공적으로 검증하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권3호
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• pp.205-212
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• 2002

The growth characteristics of metal-organic chemical vapor deposition (MOCVD) $Pb(Zr_xTi_{1-x})O_3 (PZT) thin films were investigated for the application of high-density ferroelectric random access memories (FRAM) devices beyond 64Mbit density. The supply control of Pb precursor plays the most critical role in order to achieve a reliable process for PZT thin film deposition. We have monitored the changes in the microstructure and electrical properties of films on increasing the Pb precursor supply into the reaction chamber. Under optimized conditions, $Ir/IrO_2/PZT(100nm)/Ir capacitor shows well-saturated hysteresis loops with a remanent polarization (Pr) of $~28{\mu}C/textrm{cm}^2$ and coercive voltage of 0.8V at 2.5V. Other issues such as step coverage, compositional uniformity and low temperature deposition was discussed in viewpoint of actual device application.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.105-106
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• 2006

The ferroelectric materials of the PZT, SBT attracted much attention for application to ferroelectric random access memory (FRAM) devices. Through the last decade, the lead zirconate titanate (PZT) is one of the most attractive perovskite-type materials for the ferroelectric products due to its higher remanant polarization and the ability to withstand higher coercive fields. FRAM has been currently receiving increasing attention for one of future memory devices due to its ideal memory properties such as non-volatility, high charge storage, and faster switching operations. In this study, we first applied the damascene process using chemical mechanical polishing (CMP) to the fabricate the $Pb_{1.1}(Zr_{0.52}Ti_{0.48})O_3$ thin film capacitor in order to solve the problems of plasma etching such as low etching profile and ion charging. The structural characteristics were compared with specimens before and after CMP process of PZT films. The scanning electron microscopy (SEM) analysis was performed to compare the morphology surface characteristics of $Pb_{1.1}(Zr_{0.52}Ti_{0.48})O_3$ capacitors. The densification by the vertical sidewall patterning and charging-free ferroelectric capacitor could be obtained by the damascene process without remarkable difference of the characteristics.

• Transactions on Electrical and Electronic Materials
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• 제1권4호
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• pp.30-39
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• 2000

The variation of electrical properties of (Ba, Sr)TiO$_3$[BST] thin films deposited of RuO$_2$electrode with (Ba+Sr)/Tr ration was investigated. BST thin films with various (Ba+Sr)/Tr ration were deposited on RuO$_2$/Si substrates using in-situ RF magnetron sputtering. It was found that the electrical properties of BST films depends on the composition in the film. The dielectric constant of the BST films is about 190 at the (Ba+Sr)/Tr ration of 1.0, 1,025 and does not change markedly. But , the dielectric constant degraded to 145 as the (Ba+Sr)/Tr ratio increase to 1.0. In particular, the leakage current mechanism of the films shows the strong dependence on the (Ba+Sr)/Tr ration in the films. At the ration (Ba+Sr)/Tr=1,025, the Al/BST/RuO$_2$ capacitor show the most asymmetric behavior in the leakage current density, vs, electric field plot. It is considered that the leakage current of the (Ba+Sr)/Tr=1,025 thin films is controlled by the battier-Iimited process, i,e, Schottky emission.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.407-408
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• 2005

High surface area electrodes for aluminum electrolytic capacitors are produced by AC electrochemical processes. Optimization of crystallographic etch pit growth on aluminium during AC etching of cathode film for aluminium as electrolytic capacitor has been established. In this work, we present the observations of pit distributions by galvanostatic measurements. The effects of electrolyte concentration, current density, frequency, various pre-treatments and etching time have been studied. The specimen was pretreated in 0.5M NaOH and 1M HCl at $40\sim60^{\circ}C$, and transferred into a cell containing 1M HCl, then various mol $H_2SO_4$ etchant was added. Pit size distributions were determined with scanning electron microscopy (SEM).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.207-209
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• 2019

This paper proposes a grid-tied photovoltaic (PV) system, consisting of Voltage-fed dual-active-bridge (DAB) dc-dc converter with single phase inverter. The proposed converter allows a small dc-link capacitor, so that system reliability can be improved by replacing electrolytic capacitors with film capacitors. The double line frequency free maximum power point tracking (MPPT) is also realized in the proposed converter by using Ripple Correlation method. First of all, to eliminate the double line frequency ripple which influence the reduction of DC source capacitance, control is developed. Then, a designing of Current control in DQ frame is analyzed and to fulfill the international harmonics standards such as IEEE 519 and P1547, $3^{rd}$ harmonic in the grid is directly compensated by the feedforward terms generated by the PR controller with the grid current in stationary frame to achieve desire Total Harmonic Distortion (THD). 5-kW PV converter and inverter module with a small dc-link film capacitor was built in the laboratory with the proposed control and MPPT algorithm. Experimental results are given to validate the converter performance.