• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.51-54
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• 2003

Tb-doped lead zirconate titanate($Pb_{1.1}(Zr_{0.6}Ti_{0.4})O_3$; PZT) thin films on $Pt(111)/Ti/SiO_2/Si(100)$ substrates prepared by a sol-gel method. Films have a Zr/Ti ratio of 60:40 and perovskite phase structure. The effect on the structural and electrical properties of films measured according to Tb content. Dielectric and ferroelectric properties of PZT thin films were altered significantly by Tb-doping. The PZT thin film with higher dielectric constant and improved leakage current characteristic was obtained by adding 0.3 mol% Tb. At 100 kHz, the dielectric constant and the dielectric loss of the 0.3 mol% Tb-doped PZT thin film were 1611 and 0.24, respectively The remanent polarization(2Pr) of the 0.3 mol% Tb-doped PZT thin film was $61.4\;{\mu}C/cm^2$ and the coercive field was 61.9 kV/cm. Tb-doped PZT thin films showed improved fatigue characteristics comparing to the undoped PZT thin film.

• Current Optics and Photonics
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• 제7권1호
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• pp.21-27
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• 2023

A highly sensitive optical-fiber humidity sensor is demonstrated in this paper. By using Nafion-PVA sol-gel and single-mode optical fibers, the Fabry-Perot humidity sensor is easily fabricated. In the humidity range of 29%-72%, humidity-response experiments are carried out with a cycle of rising and falling humidity to investigate humidity-response characteristics. The experimental results show 2.25 nm/%RH sensitivity and a 0.9997 linear correlation coefficient, with good consistency. The changes in optical-path difference (OPD) and free spectral range (FSR) with humidity are also discussed. The humidity sensitivities of a typical sensor are 80.3 nm/%RH (OPD) and 0.03 nm/%RH (FSR). Furthermore, many humidity sensors with different Nafion-PVA sol-gel concentration and initial cavity length are experimentally investigated for humidity response. The results show that the sensitivity increases with higher Nafion ratio of the Nafion-PVA sol-gel. The influence of changing cavity length on sensitivity is not obvious. These results are helpful to research on optical-fiber humidity sensors with good performance, easy fabrication, and low cost.

• 한국결정성장학회지
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• 제21권5호
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• pp.205-209
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• 2011

ZnO는 반도전성과 초전도성을 나타내며 광학적으로도 독특한 재료로 가스센서, 태양전지, 광학도파관 등 여러 방면에 널리 활용되고 있다. 본 논문에서는 이러한 ZnO에 Al을 첨가함에 따라 광학적 특성에 어떠한 영향을 미치는지 알아보기 위하여 ZnO에 Al 첨가량 변화에 따른 나노구조체를 제작하여 특성을 비교하였다. ZnO 용액은 PVP, ethanol, zinc acetate를 이용하여 Sol의 형태로 제작하였으며, Al첨가용액을 넣어 Al이 첨가된 ZnO Sol을 제작하였다. 제작된 Sol을 전기 방사법을 이용하여 나노구조체를 제조하였다. 제조된 섬유들을 각각 300, 500, $700^{\circ}C$로 열처리 한 후 나노 구조체를 XRD, XPS, SEM을 이용하여 분석하였다. 또한 TGA, DSC를 이용하여 온도변화에 따른 질량 및 열량의 변화를 측정하였다. UVvis를 이용하여 ZnO와 Al이 첨가된 ZnO의 흡광도를 측정 비교하였다.

• 한국결정성장학회지
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• 제22권3호
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• pp.127-133
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• 2012

박막 태양전지의 저가 고효율화를 실현하기 위해 넓은 면적의 기판 위에 코팅이 가능하며 진공의 유지가 필요가 없고 장치가 간단하며 고순도의 균질한 박막을 얻을 수 있고 박막의 조성을 쉽게 조절할 수 있는 Sol-Gel법을 이용하였다. Se보다 저가이며 독성이 없고 풍부한 원료인 S로 치환하여 사용하며 Zn/Sn비 값을 조절하고 kesterite 구조를 갖는 $Cu_2ZnSnS_4$의열처리 온도에 따른 박막의 구조적, 광학적 특성에 미치는 변수들의 영향을 알아보았다. XRD pattern을 관찰한 결과 Zn/Sn비가 0.8/1.2일 때 $2{\theta}=28.5^{\circ}$에서 주피크가 가장 강하게 나타났으며 (112) 방향의 배향성을 가진 kesterite 상임을 확인 할 수 있었다. 열처리 온도가 증가할수록 (112) 면의 강도가 커지며 $550^{\circ}C$에서 열처리를 한 $Cu_2ZnSnS_4$ 박막은 kesterite 구조의 화학량론적 $Cu_2ZnSnS_4$ 특징을 나타내고 본 실험의 샘플의 격자상수를 측정한 값이 a = 5.5047 and $c=11.014{\AA}$이며 JCPDS(Joint Committee on Powder Standards)에 보고된 데이터 a = 5.427 and $c=10.848{\AA}$과 거의 일치 하였다. 광학적 특성을 알아보기 위해 측정한 광투과율은 가시광선 영역(380~770 nm)에서 전체적으로 65 % 이하로 나타났다.

• 한국세라믹학회지
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• 제32권3호
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• pp.281-288
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• 1995

to prepare the TiO2 thin films, acetyl-acetone(2.4-pentanedione)(1 : 1 molar ratio) was dissolved in the propanol solution of titanium(IV)isopropoxide(Ti[OCH(CH3)2]4). Al, Cr and Sb in the form of soluble salt and niobium ethoxide were added s dopants, respectively. Thin films were coated by the dip-coating method and characteristics were investigated by XRD, SEM and conductance meter. As a result, viscosity of sol was maintained below 4 centi Poise more than 20 days, and crystal growth and diminution of resistivity occurred as the heat treatment temperature increased. The grains grew over 1${\mu}{\textrm}{m}$ and the lowest resistivity was obtained when Nb was added at 130$0^{\circ}C$.

• 한국세라믹학회지
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• 제29권1호
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• pp.35-40
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• 1992

Porous glass in the ZrO2-SiO2 system containing up to 30 mol% zirconia were prepared from the mixed solutions of Zr(O.nC3H7)4 and partially prehydrolyzed TEOS by the sol-gel method. Pore characteristics, physical properties and alkali resistance were investigated. The gels converted into the porous glass by heating at $700^{\circ}C$, it was found that the glass like skeleton was already made up in lower temperature regions. The specific surface area of the porous glass was 227 $m^2$/g, average mean pore size was about 19$\AA$ and porosity was 19.2%, pore characteristics and physical properties depended on heating temperature. Alkali resistance of the porous glass increased as the zirconia content increased, because of the appearance of Zr-enriched layer at glass surface.

• 한국세라믹학회지
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• 제30권1호
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• pp.17-24
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• 1993

Sol-gel spin-coating technique was used to produce Nb2O5 thin films on silicon substrates from Nb(OC2H5)5 precursor. The films were heat-treated at temperatures between $600^{\circ}C$ and 100$0^{\circ}C$ in oxygen atmosphere and their crystalline phases, chemical states, and dielectric characteristics were investigated by X-ray diffractometry (XRD), Auger electron spectroscopy (AES), and C-V measurements, respectively. After 1 hour heat-treatment at 80$0^{\circ}C$, T-type Nb2O5 was formed, and its chemical composition was homogeneous with no appreciable SiO2 oxide at interfaces between the films and substrates. The films heat-treated at temperatures between $600^{\circ}C$ and 80$0^{\circ}C$ exhibit dielectric constant of less than 20 while the films heat treated at 100$0^{\circ}C$ show dielectric constant of 28.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.31-34
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• 2006

In this study, $(Ba_{0.7}\;Sr_{0.3})TiO_3$ was coated on Pt/Ti/$SiO_2$/Si wafer by using Sol-Gel method. Coating process was repeated 3~5 times and then sintered at 750[$^{\circ}C$] for 1 hour. Each specimen was analyzed structure and electrical characteristics. In structure characteristics, EDX analyzed the samples ratio of the formation on the structural property. Thermal behavior was observed with TG-DTA and concluded that the heat-treatment of the samples was degreed 750[$^{\circ}C$]. Surface and section of thin films were observed with SEM.

• 한국세라믹학회지
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• 제34권10호
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• pp.1060-1066
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• 1997

In this paper, the effects of La addition of PLZT thin film prepared by sol-gel method on the capacitor characteristics are investigated for gigabit generation DRAM applications. The addition of La on the PLZT capacitor results in a trade-off between charge storage density(Qc') and leakage current density(Jl). As La content increases, Qc' and permeability(εr) at 0V are reduced while Jl is significantly decreased. It is demonstrated that 5% La doping of PZT can substantially reduce Jl and also improve resistance to fatigue while incurring only minimal degradation of Qc'. Very low leakage current density (5×10-7 A/㎠ even at 125℃) and high charge storage density (100fC/㎛2) under VDD/2=1V conditions are achieved using 5% La doped PZT thin films for gigabit DRAM capacitor dielectrics. In addition, the fatigue and TDDB measurements indicate good reliability of the PLZT capacitors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1472-1474
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• 1994

In this paper, $TiO_2-V_2O_5$ thin films are fabricated by Sol-Gel method and their humidity-sensing characteristics have been investigated. The microstructure of specimen is porous. The humidity-sensing characteristics of thin films are good according to increasing heat treatment temperature and decreasing measurement frequency.