Hyun-Il Kang

Effect of Annealing Temperature on the Properties of Sputtered Bi 3.25 La 0.75 Ti 3 O 12 Thin Films

(BLT) thin films were prepared on the Pt(150 nm)/Ti(50 nm)//Si substrate using the rf magnetron sputtering method. The BLT thin films were annealed at temperatures ranging from to using the rapid thermal annealing. The structure and surface morphology of the thin films were characterized by x-ray diffraction and field emission scanning electron microscopy. The hysteresis loop of the BLT thin films showed that the remanent polarization (2Pr) of the film annealed at was 10.92 . The fatigue characteristic of the BLT thin film annealed at was shown change polarization up to switching cycles. We confirmed the excellent remnant polarization (Pr) and fatigue properties compared with other fabrication methods and suggested a good method for BLT thin films fabrications.

Implementation of Prediction Program for Deterioration Judgment on Substation Power Systems in Urban Railway

In this paper, we present a deterioration judgment model of urban rail power equipment using driving history, the frequency and number of failures. In addition, we have developed a deterioration judgment program based on the derived failure rate. A deterioration judgment model of power equipments on metro system was designed to establish how much environmental factors, such as thermal cycling, humidity, overvoltage and partial discharge. The deterioration rate of the transformers followed the Arrhenius log life versus reciprocal Kelvin temperature (hotspot temperature) relation. The deterioration judgment program is linked to the online condition monitoring system of urban railway system. The deterioration judgment program is based on the user interface it is possible to apply immediately to the urban rail power equipment.

Properties of the Various Power Ratio in GZOB/AU Multilayers

We investigated the effects of power ratio on the electrical and optical properties of Au based Ga-, B- codoped ZnO(GZOB) thin films. GZOB thin films were deposited on Au based poly carbonate(PC) substrate with various power in the range from 60 to 120 W by DC magnetron sputtering. In the result, GZOB films at 100 W exhibited a low resistivity value of , and a visible transmission of 80 % with a thickness of 300 nm. This result indicated that the addition of Ga and B in ZnO films leads to the improvement of conductivity and transparent. From the result, we can confirm the possibility of the application as transparent conductive electrodes.

The Characteristics of Ga-doped ZnO Transparent Thin Films by using Multilayer

With development of electronic products the demands for miniaturization and weight-lightening have increased until a recent date. Accordingly, The effort to substitute glass substrates was widely made. However, polymer substrates have weak point that substrates were damaged at high temperature. In this paper, we deposited transparent conductive film at low temperature. And we inserted Au thin film between oxide to compensate for deteriorated electrical characteristics. Ga-doped ZnO(GZO) multilayer coatings were deposited on glass substrate by DC sputtering. The optimization of deposition conditions of both AZO and Au layers were performed to obtain better electrical and optical characteristics in advance. We presumed that the properties of multilayer were affected by the deposition process of both GZO and Au layers. The best multilayer coating exhibited the resistivity of and transmittance of 77 %. From these results, we can confirm a possibility of the application as transparent conductive electrodes.

Structural and Electrical Characteristics of Carbon Nanowalls Synthesized on the Polyimide Film

In this study, the structural and electrical characteristics of carbon nanowalls (CNWs) synthesized on polyimide films were investigated. CNWs were synthesized on polyimide films as various growth times. The cross-section and surface of the CNWs synthesized were examined using FE-SEM. The growth and defects of CNWs were observed by raman spectrum. The hall measurement system was used to analyzed sheet resistance, resistivity and conductivity. The CNWs synthesized at 40 minutes showed outstanding structural and electrical characterizations than another growth times.

Improvement of Electrical Properties of Carbon Nanowall by the Deposition of Thin Film

In this study, the improvement of the electrical properties of carbon nanowalls (CNWs) by the deposition of nonmetallic thin films such as carbon (C), silicon (Si), and silicon carbide (SiC) was investigated. The CNWs were synthesized on a Si wafer substrate using microwave-plasma-enhanced chemical vapor deposition (PECVD). The thin films were deposited through RF magnetron sputtering with a 4-inch target (C, Si, and Sic) on the grown CNWs. The surficial and cross-sectional conditions were examined using the images obtained from a field emission scanning electron microscope (FESEM). The structural characteristics were analyzed through Raman analysis. The analysis of the electric characteristics confirmed that the resistivity decreased for the nonmetallic-thin-film-coated samples, and that the mobility increased in the order of the as-deposited sample and the C-, SiC-, and Si-thin film-deposited samples. It was also confirmed that the deposition of the SiC thin films resulted in the lowest resistivity at 13.6 × 10-3 Ωcm, and that the deposition of the Si thin films showed the highest mobility at 304 cm2/VS.

Development and Performance Analysis of Carbon Nanowall-Based Mass Sensor

In this study, a mass sensor was fabricated using a carbon nanowalls, and its performance was analyzed. The substrate that was used to fabricate the mass sensor was a polyimide film, on which a SiO2 insulating layer and a copper electrode were deposited using an RF magnetron sputter. Thereafter, a carbon nanowalls was grown on the substrate until its size was 5 by 5 mm. The growth times of the completely grown carbon nanowalls were 20, 25, and 30 minutes, respectively. The performance of the mass sensors fabricated based on different carbon nanowalls grown for various growth times was analyzed according to the changing mass from 1 to 5 mg.

The Electric and Ferroelectric of Pb(Zr 0.52 Ti 0.48 )O 3 Thin Films Deposited on Ruthenium Electrodes

Abstract - Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films deposited on Ru/RuO 2 bottom electrode that grown for in-situ progress used rf magnetron sputtering method. We investigated the dependence of the crystalline and electrical properties in the way of capacitors PZT thin films. Our results show that all PZT films indicated polycrystalline perovskite structure with preferred orientation (110) and no pyrochlore phase is observed. The electric properties of the Ru improved with increasing Ru thin films thickness. A well-fabricated Ru/PZT/Ru (100 nm) /RuO 2 capacitor showed a leakage current density in the order of 2.03×10 -7 A/cm 2 as a 50 kV/cm, a remnant polarization (Pr) of 9.22 μC/cm 2 , and a coercive field (-EC) of -32.22 kV/cm. The results show that Ru/Ru/RuO 2 bottom electrodes are expected to reduce the degradation ferroelectric fatigue and excellent ferroelectric properties.Key Words : PZT, Perovskite, Leakage current, Ruthenium† 교신저자, 정회원 : 국립한밭대학교 전기공학과 조교수E-mail : hikang@hanbat.ac.kr*정 회 원 : 서일대학교 전기과 조교수** 정 회 원 : 여주대학 전기과 교수***정 회 원 : 여주대학 방송제작연예과 부교수 접수일자 : 2013년 11월 5일수정일자 : 2013년 11월 28일 최종완료 : 2013년 11월 29일

Growth Properties of Carbon nanowall according to the Reaction Gas Ratio

Abstract - Graphite electrodes are used for secondary batteries, fuel cells, and super capacitors. Research is underway to increased the reaction area of graphite electrodes used carbon nanotube (CNT) and porous carbon. CNT is limited to device utilization in order to used a metal catalyst by lack of surface area to improve. In contrast carbon nanowall (CNW) is chemically very stable. So this paper, microwave plasma enhanced chemical vapor deposition (PECVD) system was used to grow carbon nanowall (CNW) on Si substrate with methane (CH 4 ) and hydrogen (H 2 ) gases. To find the growth properties of CNW according to the reaction gas ratio, we have changed the methane to hydrogen gas ratios (4:1, 2:1, 1:2, and 1:4). The vertical and surficial conditions of the grown CNW according to the gas ratios were characterized by a field emission scanning electron microscopy (FE-SEM) and Raman spectroscopy measurements showed structure variations. Key Words : Carbon nanowall (CNW), Reaction gas ratio, Growth properties, Microwave plasma enhanced chemical vapor deposition (PECVD)† Corresponding Author : Dept. of Electrical Engineering, Hanbat National University, KoreaE-mail : wschoi@hanbat.ac.kr*Hanbat National University, Korea** Yeoju Institute of Yechnology, Korea***Seoil University, Korea§Kangwon National University, Korea접수일자 : 2014년 2월 4일수정일자 : 2014년 9월 23일최종완료 : 2014년 10월 28일

Improvement of the Characteristics of PZT Thin Films deposited on LTCC Substrates

본 논문에서는 실리콘 기반의 기술과 차별화하여 저온동시소성세라믹 (LTCC) 기판을 이용하여 대표적 압전물질인 PZT 박막의 최적의 증착조건을 연구하였다. LTCC 기술은 실리콘 기반의 기술에 비하여 낮은 생산 단가, 높은 수율, 3차원 구조물의 용이한 제작성 등으로 인하여 센서 및 액추에이터와 같은 10 um ~ 수백 um 정도의 중규모 디바이스를 제작하는데 있어서 중요한 역할을 담당하고 있다. LTCC 기판은 NEG사의 MLS 22C 상용 파우더를 이용하여 100 um 두께의 그린쉬트를 적층하고 동시소결하여 400 um 두께로 제작하였다. 제작한 기판위에 Pt/Ti 하부전극을 증착하고 RF 마그네트론 스퍼터링 방법을 이용하여 PZT 박막의 증착조건을 연구하였다. 증착조건으로는 RF 전력과 아르곤과 산소 가스비를 가변하여 실시하였으며, XRD와 EDS를 사용하여 박막의 결정성 및 성분을 분석하였다. 실험을 통하여 얻어진 최적의 증착조건은 RF 전력 125W, 아르곤과 산소비 15:5에서 가장 우수한 특성을 나타내는 것을 확인하였다. 【In this paper, the optimized growing conditions of PZT thin films on low temperature co-fired ceramics (LTCC) substrates are studied. The LTCC technology is an emerging one in the fields of mesoscale (from 10 um to several hundred um) sensor and actuator against silicon based technology due to low cost, high yield, easy manufacturing of 3 dimensional structure, etc. The LTCC substrates with thickness of 400 um are fabricated by laminating 100 um green sheets using commercial power (NEG, MLS 22C). The Pt/Ti bottom electrodes are deposited on the LTCC substrates, then the growing conditions of PZT thin films using rf magnetron sputtering method are studied. The growing conditions are tested under various rf power and gas ratio of oxygen to argon. And the crystallization and ingredient of PZT films are analyzed by X-ray diffraction method (XRD) and energy dispersive spectroscopy (EDS). The optimized growing conditions of PZT thin films are rf power of 125W, Ar/O2 gas ratio of 15:5.】