• Korean Journal of Materials Research
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• v.10 no.10
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• pp.684-690
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• 2000

In order to study effects of interfacial layers between $Pb(Zr,Til)Q_3(PZT)$ films and electrodes for Metal-Ferroelectric-MetaI(MFM) structure capacitors, we have fabricated the capacitors with the Pt/PZT/interfacial-layer/Pt/$TiO_2/SiO_2$/Si structure. $PbTiO_3(PT)$ interfacial layers were formed by sol-gel deposition and PbO, ZrO, and $TiO_2$ thin layers were deposited by reactive sputtering. $TiO_2$ interface layers result in the finest grains of PZT(crystalline Temp. $600^{\circ}C$) films compare to $PbO_2\;and\;ZrO_2$ layers. However, as the thickness of $TiO_2$ layer increases. PZT thin films become rough and electrical characteristics were deteriorated due to remained anatase phase. On the other hand. PT interface layers result in improved morphology of PZT films and do not significantly change ferroelectric properties. It is a also observed that seed layers at the middle and top of PZT films do not give significant effects on grain size but the PT seed layer at the interface between the bottom electrode and the PZT films results in the small grain size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.175-179
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• 1996

Ferroelectric SrBi$_2$Ta$_2$$O_{9}$ thin films were fabricated by tole Sol-Gel method using a spin-on coating with MOD(Metal Organic Dccomposition) solution on Pt/Ti/SiO$_2$/Si(100) substratcs. The films were anncalcd at 80$0^{\circ}C$ for one hour in oxygen atmosphere. The effects of Bi/Ti mole ratios on crystalline orientations, surface morphologies, and subface composition SBT thin films with a Bi/Ta mole ratios from 1.1 to 1.3 were investigated using X-ray Diffractometry (XRD). Atomic Force (AFM), X-Ray Photoelectron Spectroscopy(XPS). Ferroelectric properties of these films were also measured.d.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.933-938
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• 2002

(Ba,Sr)TiO$_{4}$ (BST) thin films on Pt/Ti/SiO$_{2}$/Si substrates were deposited by a sol-gel method and the etch characteristics of BST thin films have been investigated as a function of gas mixing ratio. The maximum etch rate of the BST films was 440 $AA$/min under such conditions as: CF$_{4}$(CF$_{4}$＋Ar) of 0.2, RF-power of 700 W, DC-bias voltage of -200 V, pressure of 15 mTorr and substrate temperature of 30 $^{circ}C$. The selectivities of BST to Pt, SiO$_{2}$ and PR were 0.38, 0.25 and 0.09, respectively. In the XPS (X-ray photoelectron spectroscopy) analysis, Barium (Ba) and Strontium (Sr) component in BST thin films formed low volatile compounds such as BaFx, SrFx, which are forms by the chemical reaction with F atoms and is removed by Ar ion bombardment. Titanium (Ti) is removed by chemical reaction such as TiF with ease. The result of secondary ion mass spectrometry (SIMS) analysis confirmed the existence of the BaFx, SrFK, TiFx.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.51-61
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• 2003

Pollution purification using titanium dioxide (TiO$_2$) photocatalyst has attracted a great deal of attention with increasing number of relent environmental problems. Currently, the application of TiO$_2$ photocatalyst has been focused on purification and treatment of waste water. However. the use of conventional TiO$_2$ powder photocatalyst results in disadvantage of stirring during the reaction and of separation after the reaction. And the usage of artificial UV lamp has made the cost of photocatalyst treatment system high. Consequently, we herein studied the pilot-scale design to aid in optimization of the energy-saving process for more through development and reactor design by solar light/UV lamp/ TiO$_2$system. In this study, we manufactured the TiO$_2$sol by sol-gel method. According to analysis by XRD, SEM and TEM, characterization of TiO$_2$ sol were nano-size (5-6 nm) and anatase type. Inorganic binder (SiO$_2$) was added to TiO$_2$ lot to be coated for support strongly, and support of ceramic bead was used to lower separation rate that of glass bead The influences were studied of various experimental parameters such as TiO$_2$ quantity, pH, flow rate. additives, pollutants concentration, climate condition and reflection plate by means of reaction time of the main chararteristics of the obtained materials. In water treatment system, variable realtor as solar light/ or UV lamp according to climate condition such as sunny and cloudy days treated the phenol and E-coli(Escherichia coli) effectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.424-424
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• 2013

Ce3+, Sm3+, Eu3+, Tb3+ 등 희토류를 도핑한 여러 종류의 형광체는 백색 LED (white light-emitting diode), 전계방출표시소자(field emission display), 플라즈마디스플레이패널(plasma display panel), 약물 운송(drug delivery) 등 다양한 분야에서 응용되고 있다. 최근에는 졸-겔 방법(sol-gel method)을 이용하여Y2SiO5, Y3-XGdxAl5O12, SrAl2O4 등 여러 종류의 호스트 물질을 합성하여 형광체의 특성을 분석하는 연구가 활발히 진행되고 있다. 이러한 졸-겔 방법은 비교적 낮은 온도에서 간단한 공정으로 좋은 균질성과 높은 생산성을 갖도록 형광체를 제작할 수 있는 장점을 가지고 있다. 이에 본 연구에서는 졸-겔 방법을 이용하여 BaGd2TiO13구조를 제작하였고, 이러한 구조적, 광학적 특성을 분석하기 위하여 열분석기(thermal analyzer), 전계방출형주사전자현미경(field emission scanning electron microscopy), 투과전자현미경(field emission transmission electron microscopy)을 이용하였다. 이러한 졸-겔 방법을 이용하여 제작한 BaGd2TiO13 구조의 형광체 적용 연구를 통한 디스플레이 및 백색 LED 응용에 유용할 것으로 기대된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.290-293
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• 1999

(Ba$_{0.5}$Sr$_{0.5}$)TiO$_3$ thin films were fabricated at different RTA temperatures and thicknesses by Sol-Gel method. Solution consisting of acetate powders and titanium isopropoxide in a mixture of acetic acid and ethylene glycol were spin coated onto Pt/Ti/SiO$_2$/Si substrates. The films were annealed in the temperature range of 650~80$0^{\circ}C$ for 3 minutes by rapid thermal annealing. These BST thin films were fully crystallized at 75$0^{\circ}C$ and showed a maximum dielectric constant value of $\varepsilon$$_{r}$=~468 and dielectric loss was ~0.025 at a thickness of approximately 4000$\AA$.EX>.>.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1434-1436
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• 1996

In this study, ferroelectric $PbTiO_3$ thin films were deposited on the Pt/$SiO_2$/Si substrate by Sol-Gel method. $PbTiO_3$ stock solution was made and spin-cooled at 4000[rpm] for 30[sec.]. Coated specimens were dried at $400[^{\circ}C]$ for 10[min.] and then annealed at $500{\sim}800[^{\circ}C]$ for 1 hour. Annealing temperature were examined to optimize micro structural and dielectric properties of the films. The ferroelectric perovskite phase was observed in the file annealed at $700[^{\circ}C]$ for 1 hour. In the case of $PbTiO_3$ thin films annealed at $700[^{\circ}C]$ for hour, dielectric constant and dielectric loss showed the good value of 324, 2.0[%], respectively.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.177-181
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• 2001

We have studied superhydrophilic properties of TiO₂thin films in relation with those crystal structures due to the heat treatments. Thin films were fabricated on Si (100) wafers using a conventional Sol-Gel method. Following drying and sintering processes, TiO₂film had an anatase phase with additional heat treatment at 500℃, an rutile phase at 1000℃, and a mixture of anatase and rutile phase at 750℃. All these films got hydrophilic even without any UV illumination. Especially the sample treated at 750℃ had a superhydrophilic contact angle of 5°. We suggested that the superhydrophilic films should have a mixture of anatase and rutile phase for the best performance. The hydrophilic TiO₂films were slowly degraded into the hydrophobic state in the dark room but quickly recovered back with les than 1 hour of UV illumination.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.43-46
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• 2002

Ferroelectric Mg-doped SBT and Ti-doped SBT were successfully deposited on Pt/Ti/$SiO_2/Si$ substrate by using a sol-gel solution coating method. The solutions were prepared through out adding the metal alkoxide solutions to SBT solution. The typical hysteresis loop of the films was obtained at 5V. The measured $2P_r$ value were $16.50{\mu}C/cm^2$ for SBT, $18.98{\mu}C/cm^2$ and for Mg-doped SBT, and $17.10{\mu}C/cm^2$ for Ti-doped SBT at an applied voltage of 5V, respectively. And it is found that the leakage current densities are less than $10^{-7}A/cm^2$ when applied voltage is less than 10.8MV/cm, which indicates the excellent insulating characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.648-651
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• 2004

Pb0.5Sr0.5TiO3(PST) thin films were deposited on the LaNiO3 (LNO(100))/Si and Pt/Ti/SiO2/Si substrates by the alkoxide-based sol-gel method. Structural and dielectric properties of PST thin films for the tunable microwave device applications were investigated. The PST films, which were directly grown on the Pt/Ti/SiO2/Si substrates showed the random orientation. For the LNO/Si substrates, the PST thin films exhibited highly (100) orientation. Compared with randomly oriented films, the highly (100)-oriented PST thin films showed better dielectric constant, tunability, and figure of merit (FOM). The dielectric constant, tunability, and FOM of the highly (100)-oriented PST thin film increased with increasing annealing temperature due to the decrease in lattice distortion. The differences in dielectric properties may be attributed to the change in the film stress and the in-plane oriented Polar axis depending on the substrate was used. The dielectric constants, dielectric loss and tunability of the PST thin films deposited on the LNO/Si substrates measured at 1 MHz were 483, 0.002, and 60.1%, respectively.