• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.166-166
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• 2010

Recently, TFTs based on amorphous oxide semiconductors (AOSs) such as ZnO, InZnO, ZnSnO, GaZnO, TiOx, InGaZnO(IGZO), SnGaZnO, etc. have been attracting a grate deal of attention as potential alternatives to existing TFT technology to meet emerging technological demands where Si-based or organic electronics cannot provide a solution. Since, in 2003, Masuda et al. and Nomura et al. have reported on transparent TFTs using ZnO and IGZO as active layers, respectively, much efforts have been devoted to develop oxide TFTs using aforementioned amorphous oxide semiconductors as their active layers. In this thesis, I report on the performance of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer at room temperature. $SiO_2$ was employed as the gate dielectric oxide. The amorphous indium gallium zinc oxides were deposited by RF magnetron sputtering. The carrier concentration of amorphous indium gallium zinc oxide was controlled by oxygen pressure in the sputtering ambient. Devices are realized that display a threshold voltage of 1.5V and an on/off ration of > $10^9$ operated as an n-type enhancement mode with saturation mobility with $9.06\;cm^2/V{\cdot}s$. The devices show optical transmittance above 80% in the visible range. In conclusion, the fabrication and characterization of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer were reported. The operation of the devices was an n-type enhancement mode with good saturation characteristics.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.205-210
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• 2008

Titanium-doped indium oxide (ITiO) films were prepared on soda-lime glass substrate using a magnetic null discharge (MND) sputter source. The ITiO thin films containing 10wt.% Ti showed the minimum resistivity of $\rho=5.5{\times}10^{-3}{\Omega}-cm$. The optical transmittance increases from 70% at 450 nm to 80% at 700 nm in visible spectrum. Photoelectron peaks for In 3d, Ti 2p, O 1s and C1s were detected for the ITiO film in the binding energy range of 0 to 1100 eV. The surface roughness of the sample showed a change from 10 nm to 50 nm. The ITiO film used for TCO layer of DSCs exhibited an energy conversion efficiency of about 3.8% at light intensity of 100 mW/$cm^2$.

• 한국안광학회지
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• 제6권2호
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• pp.31-35
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• 2001

$TiN_xW_y$ 전도박막층으로 무반사, 무정전 광학박막을 Essential Macleod 프로그램을 이용하여 설계한 결과 [공가 ${\mid}TiN_xW_y{\mid}SiO_2{\mid}$ 유리]층은 단 두층코팅막으로 가시광선 파장영역 (450~700 nm)에서 넓게 AR 코팅이 되었다. RF magnetron 스퍼터링 장치에 질소가스와 아르곤가스를 동시에 주입하면서 Ti 타켓을 스퍼터링하여 $TiN_x$ 광학박막을 7 nm에서 10 nm의 두께로 유리기판 위에 제작하였다. 이 때 박막의 화학적 조성과 성분비를 분석하기 위해 XPS를 사용하였고, 박막의 면저항과 화화적 조성과의 관계를 분석하기 위하여 XPS depth profiling과 4점탐침법을 사용하였다.

• 한국재료학회지
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• 제8권12호
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• pp.1152-1157
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• 1998

금속 타겟들을 이용한 반응성 스퍼터링법으로 $460~540^{\circ}C$범위에서 $Pt/Ti/SiO_2$/Si 기판위에 PZT 박막을 증착하였다. Perovskite상의 핵형성을 위해 Pb 휘발이 적은 저온($480^{\circ}C$)에서 짧은 시간 동안 PZT 박막을 증착한 후 Pb가 PBT 박막내에 과잉으로 함유되는 것을 억제하기 위하여 증착 온도를 증가시켜 박막을 증착하는 2단계 증착법을 사용한 결과 54$0^{\circ}C$의 고온에서도 perovskite 단일상과 화학양론비에 가까운 조성을 얻을 수 있었다. 2단계 증착법으로 제조된 PZT 박막은 우수한 전기적 특성을 나타내었으며 후속 RTA 처리로 더욱 특성을 향상시킬 수 있었는데 $17\mu$C/$\textrm{cm}^2$의 잔류분극, 45kv/cm의 coercive field, 그러고 -500kv/cm의 높은 전기장에서도 $10^{-4}$ A/$\textrm{cm}^2$의 양호한 누설전류 특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.93-96
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• 2002

In this study, PZT thin films were fabricated using sol-gel processing onto Si/$SiO_2$/Ti/Pt substrates. PZT sol with different Zr/Ti ratio(20/80, 30/70, 40/60, 52/48) were prepared, respectively. The films were fabricated by using the spin-coating method on substrates. The films were heat treated at $450^{\circ}C$, $650^{\circ}C$ by rapid thermal annealing(RTA). The preferred orientation of the PZT thin films were observed by X-ray diffraction(XRD), and Scanning electron microscopy(SEM). All of the resulting PZT thin films were crystallized with perovskite phase. The fine crystallinity of the films were fabricated. Also, we found that the ferroelectric properties from the dielectric constant of the PZT thin films were over 600 degrees, P-E hysteresis constant. And the leakage current densities of films were lower than $10^{-8}A/cm^2$. It is concluded that the PZT thin films by sol-gel process to be convinced of application for ferroelectric memory device.

• 한국결정성장학회지
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• 제4권2호
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• pp.199-209
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• 1994

Titanium tetra iso-propoxide와 Lead acetate trihydrate를 출발물질로 사용하여 제조한 졸을 현미경용 soda-lime-silica 슬라이드 유리, Si-Wafer 및 Sapphire 기판 위에 Dip-coating법으로 박막을 제조하였으며, 안정한 졸을 얻기 위하여 Acetylacetone을 첨가하였다. 졸의 점도, 조성등의 영향을 조사하였고, 조성변화, 막의 두께 변화, 열처리 온도에 따른 가시영역에서의 투과율과 굴절율 및 IR Spectra를 측정하였으며, $PbTiO_3$ 박막의 결정 생성 유무를 XPD로 검토하였다. 또하 EDX로 슬라이드 유리에서 박막으로의 확산 유무를 조사하였다. 제조된 졸은 20일동안 침전없는 안정한 상태를 유지하였다. 가시영역에서의 투과율은 열처리온도와 막의 두께가 증가함에 따라 감소하였고, flat한 투과특성을 나타내었다. 슬라이드 유리 위에 코팅한 $PbTiO_3$ 박막은 $600^{\circ}C$에서 열처리한 경우 Pyrochlore형이 나타났고, Si-Wafer와 Sapphire 기판 위에 코팅할 경우에는 $600^{\circ}C$에서 Pyrochlore형이 나타나기 시작하였으며, 열처리 온도가 높아짐에 따라 $800^{\circ}C$에서 $PbTi_3O_7$상이 나타났다.

• 전자공학회논문지D
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• 제34D권5호
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• pp.22-31
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• 1997

We have measured the optical properties, thickness, and energy band gap of the P $b_{1-x}$/100/L $a_{x}$100/ $Ti_{1-}$0.25x/100/ $O_{3}$ (PLT(x)) thin film prepared by the sol-gel method with varying the La concentration, x, fyom 15 nto 33 mol%. We have obtained the values from the tranmission spectrum and employed the envelope method in anayzing the spectrum. We have also performed the simulation of the transmission spectrum on the PC (personal computer) to verify the accuracy of the values 15 to 33mol%, the refractive index (at .lambda.=632.8nm) increases from 2.39 to 2.44. The extinction coefficient does not depend on the la concentration but mainly on te wavelength, and has the values between 0.2 and 0.5 at the wavelength shorter than 330nm and between 0.001 and 0.008 at the wavelength longer than 700nm. The energy band gap of the PLT (x) thin film has been obtained on the assumption of the direct band-to-band transition. It decreases from 3.28 to 3.17eV as the La concentration increases from 15 to 33 mol%. The thickness of the PLT(x) thin film has been also obtained in high accuracy by the envelope method..

• 한국응용과학기술학회지
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• 제20권2호
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• pp.148-153
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• 2003

Electron transfer through an Langmuir-Blodgett(LB) monolayer film sandwiched between metal electrodes. We used an eicosanoic acid material and the material was very famous as a thin film insulating material. Eicosanoic acid monolayer was deposited by Langmuir-Blodgett(LB) technique and a subphase was a $CdCl_2$ solution as a 2${\times}10^{-4}$ mol/L. Also we used a bottom electrode as an Al/$Al_2O_3$ and a top electrode as a Al and Ti/Al. Here, the $Al_2O_3$ on the bottom electrode was deposited by thermal evaporation method. The $Al_2O_3$ layer was acted on a tunneling barrier and insulating layer in tunnel diode. It was found that the proper transfer surface pressure for film deposition was 25 mN/m and the limiting area per molecule was about 24 ${\AA}^2$/molecule. When the positive and negative bias applied to the molecular device, the behavior shows that a tunnel switching characteristics. This result were analyzed regarding various mechanisms.

• 한국환경과학회지
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• 제14권2호
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• pp.221-230
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• 2005

Catalytic wet oxidation of trichloroethylene (TCE) in water has been conducted using $TiO_2-supported$ cobalt oxides at $36^{\circ}C$ with a weight hourly space velocity of $7,500\;h^{-1}.\;5\%\;CoO_x/TiO_2$, prepared by using an incipient wetness technique, might be the most promising catalyst for the wet oxidation although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. XPS spectra of both fresh and used Co surfaces gave different surface spectral features for each $CoO_x,\;Co\;2P_{3/2}$ binding energy for Co species in the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of $CoTiO_x$ such as $CO_2TiO_4\;and\;CoTiO_3$. The used catalyst exhibited a 780.3-eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly $Co_3O_4$. XRD patterns for $5\%\;CoO_x/TiO_2$ catalyst indicated that the phase structure of Co species in the catalyst even before reaction is quite comparable to the diffraction lines of external $Co_3O_4$ standard. A model structure of $CoO_x$ present predominantly on titania surfaces would be $Co_3O_4$, encapsulated in thin-film $CoTiO_x$ species consisting of $Co_2TiO_4$ and $CoTiO_3$, which may be active for the decomposition of TCE in a flow of water.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.8-11
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• 2001

In this study. the recovery of plasma induced damage in the etched PZT thin film with $O_2$ re-annealing have been investigated. The PZT thin films were etched as a function of $Cl_2/Ar$ and additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etch rates of PZT thin films were $1600\dot{A}/min$ at $Cl_{2}(80%)/Ar(20)%$ gas mixing ratio and $1970\dot{A}/min$ at 30 % additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etched profile of PZT films was obtained above 70 by SEM. In order to recovery properties of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures in $O_2$ atmosphere. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed sample is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From XPS analysis, intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of TixOy is recovered by $O_2$ recombination during rapid thermal annealing process. From AFM images, it shows that the surface roughness of re-annealed sample after etching is improved.